Brandis Sextant Taxonomy, Part Seven: Outlier Sextants

Several Brandis sextants I’ve come across aren’t like of any of the five sextant types I’ve discussed in previous posts.  One of these outliers is a sextant with Brandis serial number 5687 (Figure 1).  Brandis 5687’s frame has one straight and one curved lateral brace connecting its radial arms, like the U.S. Navy Surveying Sextant illustrated in Brandis Catalog No. 20 (Figure 2).  Because of its frame pattern, I initially thought that Brandis 5687 was a surveying sextant but then I noticed that its arc scale is graduated in 10-minute intervals (Figure 3).  U.S. Navy surveying sextant specifications published in 1897, 1901, and 1918 require the arc scales of surveying sextants made for the Navy to be graduated in 20-minute intervals, so Brandis 5687 isn’t a surveying sextant, at least not according to these specifications.

Figure 1.  Brandis 5687

Figure 2. Brandis Catalog No. 20

Figure 3.  Brandis 5687's Arc Scale

Brandis 5687 was the first sextant of its type that I came upon, but eventually I found two more like it; their Brandis serial numbers are 5965 and 6028, respectively.  I came upon all three of these sextants on eBay, and so all I know about them is what I can see in the photos posted in their eBay listings and what little their sellers had to say about them.  As far as I can tell, none of these sextants are marked with a Naval Observatory serial number but it may be that the photos provided in their eBay listings don’t happen to show them.  I’ll note here that the eBay listing for Brandis 5965 reported its box to have dimensions of 10” x 10” x 5.5”, which matches the dimensions of Brandis surveying sextant boxes.  That tells me that sextants of this type have the same frame radius, 6 inches, as a Brandis surveying sextant.

The U.S. Navy’s high grade sextant specifications published in 1897 requires the arc scales of high grade sextants to be graduated in 10-minute intervals. Brandis 5687 meets this requirement, but it fails to meet an additional requirement in these specifications that high grade sextants have at least two curved lateral braces connecting their radial arms. The frame pattern of Brandis 2864 (Figure 4), which was discussed in my earlier post on Brandis high grade sextants, conforms with this specification as does the frame pattern of the high grade sextant illustrated in Brandis Catalog No. 20 (Figure 2).

Figure 4. Brandis 2864

So far we’ve looked at how Brandis 5687’s frame and arc scale compare to those of Brandis surveying sextant and high grade sextants. Let’s next look at how Brandis 5687’s tangent screw compares to the tangent screws that sextants of these two types are fitted with.  The U.S. Navy’s surveying sextant specifications published in 1901 requires surveying sextants to have a 2.75-inch long, two-headed tangent screw, while the Navy’s specifications for high grade sextants published in 1897 requires high grade sextants to have a 4.1-inch long, single-headed tangent screw.  The surveying and high grade sextants illustrated in Brandis Catalog No. 20 (Figure 5) appear to be fitted with the tangent screws called for in these specifications, so it seems that the Navy sextant specifications in effect when Brandis Catalog No. 20 was published called for the same kind of tangent screws that the earlier specifications did.  What kind of tangent screw is Brandis 5687 fitted with? The photo in Figure 1 shows us that it has a short, two-headed tangent screw. Photos I have of Brandis 5965 and Brandis 6028 show that they too, are fitted with a short, two-headed tangent screw.

Figure 5  Tangent Screws, Brandis Catalog No. 20

As a final point of comparison, let’s consider how Brandis 5687’s sighting devices compare to those of Brandis surveying and high grade sextants.  Both the U.S. Navy’s surveying sextant specifications published in 1901 and its high grade sextant specifications published in 1897 require instrument manufacturers to furnish these sextants with a sighting tube, short telescope, and long telescope.  These three devices can be seen in the illustration of the surveying in Brandis Catalog No. 20.  They also can be seen in the illustration of the high grade sextant in Brandis Catalog No. 20, but an additional device appears in this illustration as well.  That additional device is a second eyepiece for the high grade sextant’s long telescope.  The Navy’s 1901 surveying sextant specifications requires a surveying sextant’s long telescope to be furnished with an eyepiece providing a magnification of six diameters, while the Navy’s 1897 high grade sextant specifications require the long telescope of a high grade sextant to be furnished with two eyepieces providing magnifications of six and twelve diameters, respectively. Apparently, the sextant specifications in effect when Brandis Catalog No. 20 was published were the same as these earlier specifications with respect to the sighting devices these two sextant types were to be provided with.  A photo of the sighting tube, short telescope, long telescope, and second eyepiece for the long telescope of a high grade sextant, in this case the high grade sextant Brandis 2864, can be seen in Figure 6.  The way these four devices are stored in Brandis 2864’s box can be seen in Figure 7.  The holder for the long telescope is at the bottom right of the box, while the holder for the sighting tube, short telescope, and long telescope is at the box’s rear right corner.  In the photo in Figure 8 of Brandis 5687 in its box, a sighting tube, short telescope and long telescope, can be seen but not a second eyepiece for the long telescope.  We can be sure that the photographer didn’t neglect to include a second eyepiece in this photo, because this photo shows that the holder in the corner of Brandis 5687’s box doesn't have a space to hold such a thing.  So Brandis 5687’s long telescope has only one eyepiece, and in this respect Brandis 5687 is like a surveying sextant. Photos that I have of Brandis 5965 and Brandis 6028 show that their long telescopes, too, were supplied with only one eyepiece.

                                                     Figure 6. Brandis 2864 Sighting Devices (l to r):                                                                    Second Eyepiece for Long Telescope, Sighting Tube, Short Telescope, Long Telescope.

Figure 7.  Brandis 2864 Box with Sighting Devices in their Holders

Figure 8. Brandis 5687 in its Box, with Sighting Devices

Brandis 5687 and other sextants of its type are like Brandis surveying sextants in terms of their frame pattern, tangent screw, and the sighting devices with which they were provided, but their arc scales are graduated like the arc scales of Brandis high grade sextants. Sextants like Brandis 5687 don’t appear in any Brandis product literature I’ve seen and so I don’t know what name Brandis had for them  Until I have a better idea what sextants like Brandis 5687 were called, I’ll refer to them as ‘Type 6 sextants’, simply because they are the sixth type of sextant I’ve discussed.

A photo of second type of outlier sextant that I’ve come across appears in Figure 9.  Its Brandis serial number is 5981 and it is also marked with U.S. Naval Observatory serial number 1142.  What sets Brandis 5981 apart from the sextants discussed in previous posts is that its frame has three curved lateral braces connecting its radial arms.  Brandis 5981’s arc scale is marked in 10-minute increments, like the arc scale of a high grade sextant.  Brandis 5981’s frame pattern is different than the high grade sextant depicted in Brandis Catalog No. 20, but it nevertheless conforms with the U.S. Navy’s 1897 high grade sextant specifications, which requires high grade sextant frames to have at least two lateral braces.  Brandis 5981’s tangent screw is long and single-headed as required by these specifications, and its long telescope has two eyepieces, which also meets the requirements in these specifications.

Figure 9 Brandis 5981

As was the case for the Type 6 sextants, I don’t have any Brandis product literature that indicates the name Brandis had for sextants of this type. A partial scrap of the U.S. Naval Observatory inspection certificate inside the lid of Brandis 5981's box is not legible in the photo I have of it, which is unfortunate, because that certificate might have told us what the U.S. Navy called sextants like it [1].  Until I find something that tells me what sextants like Brandis 5981 were called, I’ll unimaginatively refer to them as Type 7 sextants.

Brandis 5981 isn’t the only Type 7 sextant I’ve come across.  Another sextant of this type has Brandis serial number 5851 and is marked with U.S. Naval Observatory number 1110.  Brandis 5981 and Brandis 5851 have some of the highest Brandis serial numbers I’ve seen, yet their Naval Observatory serial numbers are lower than most Brandis sextants I’ve seen.  That is something that is worth further discussion, but I’ll save that discussion for some future post.

Once I became aware of the existence of Type 7 sextants I realized that I’d seen a photo of a Brandis sextant frame with three curved lateral braces in Bill Morris’s book, The Nautical Sextant.  The frame, separated from the rest of the sextant, appears on a page comparing the similarly detached frames of sextants from several different manufacturers.  I contacted Mr. Morris to learn more about this sextant, thinking it was another Type 7 sextant.  What he told me about this sextant, whose Brandis serial number 5191, suggests that it is yet another type of Brandis sextant.  Mr. Morris reports that Brandis 5191’s vernier scale is graduated to provide a 30-second reading precision.  As we’ve seen, the arc scales of Type 7 sextants are graduated in 10-minute intervals.  In my experience looking at Brandis and other sextants, I’ve pretty consistently found that sextants with vernier scales providing a 10-second reading precision have arc scales graduated in 10-minute intervals, and sextants with vernier scales providing a 30-minute reading precision have arc scales graduated in 20-minute intervals.  The U.S. Navy sextant specifications referred to earlier in this post in fact require these particular pairings of vernier scale reading precisions with arc scale graduations. The 1901 surveying sextant specifications require an arc scale graduated in 20-minute intervals and a vernier scale providing a 30-second reading precision, while the 1897 high grade sextant specifications required an arc scale graduated in 10-minute intervals and a vernier scale providing a 10-second reading precision.  The 30-second reading precision of Brandis 5191’s vernier scale suggests to me that Brandis 5191’s arc scale is graduated in 20-minute intervals, and so I’m tentatively taking Brandis 5191 to be an example of yet another Brandis sextant type, which I will refer to as a Type 8 sextant.  I will reach out to Mr. Morris and ask him specifically how Brandis 5191’s arc sale is graduated and what kind of tangent screw it is fitted with.  As of this post’s publication date, I’ve seen no other sextant like Brandis 5191, so it is an outlier even among the outlier Brandis sextant types discussed in this post.

This was a difficult post to write.  I didn’t report every bit of information that I have about these different sextant types or fully flesh out my assumptions because to do so would have required digressions that I felt were too lengthy.  Classifying these outlier sextants as belonging to three types distinctly different from each other and from the sextant types discussed in earlier posts was a useful way to organize my discussion of them, but it may not be the way people classified them back when Brandis was making them.  For instance, it could be that what I’ve categorized as a Type 7 sextant was simply a later, beefed-up version of the U.S. Navy High Grade sextant featured in Brandis Catalog No. 20.  If and when any new information comes in about any of these outlier sextant types that helps to better understand them, I will update this post or write a post to update what appears here.

Comments, corrections, additional relevant facts, differing viewpoints, etc., are always welcome.  Send to gardnersghost@gmail.com
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Footnote
[1]  Naval Observatory inspection certificates have a line where the sextant’s type was usually, but not always, been entered. 

The Mystery of the RO Numbers

In my research on the origins of the Nikumaroro sextant box, I’ve come across dozens of sextants that were made for the U.S. Navy and inspected at the U.S. Naval Observatory in the early decades of the 20th century.  These sextants can be recognized by the Naval Observatory serial numbers scratched into their limbs.  The Naval Observatory serial numbers I’ve seen on these sextants are four digits long or less and are invariably preceded by the Naval Observatory 'NO' hallmark, i.e., the letter ‘N’ inscribed in the letter ‘O’.  All the sextants marked in this way were made by American manufacturers, and while most of them were made by Brandis and Sons, I’ve also seen sextants made by three other companies, Keuffel & Esser, Buff & Buff, and Stackpole & Brother, and a very old sextant box that originally held a Warner & Swasey sextant [1].  The boxes for many of these sextants contain a certificate prepared by the U.S. Naval Observatory providing corrections to apply for small angular measurement biases specific to each sextant.

A Typical Naval Obsevatory 'NO' Marking

A Naval Observatory Inspection Certificate

Five sextants that I’ve seen have markings that indicate that they were once in the U.S. Navy’s possession and that they were inspected at the Naval Observatory, but they are distinctly different from the sextants I’ve just described.  One sextant's frame has a bell-like outline, within which there are three circular rings abutting arranged in a triangular pattern.  Neatly inscribed in its limb is ‘Cairns, 12 Waterloo Road, Liverpool’; ‘Cairns’ apparently refers to Alexander Cairns, a instrument dealer in Liverpool, England, during the third quarter of the 19th century [2].  Scratched into the limb is ‘US Navy’ followed by an ‘R’ inscribed in an ‘O’ and then the number 11317.

Cairns Sextant Limb Markings

Another sextant is in the New Bedford Whaling Museum’s collection, donated by the family of a late 19th century New Bedford whaling captain named Daniel W. Gifford.  A museum catalog indicates that the limb is marked ‘Spenser, Browning & Co London’, ‘US Navy’, and the ‘RO’ symbol followed by the number 16977 [3].  Spenser, Browning & Company was a navigational instrument maker in London, England, in the middle decades of the 19th century [4].

The Captain Gifford Sextant

A third sextant, also made by Spenser, Browning & Co., appeared in the online catalog of an antiques dealer [5].  The inside of the sextant’s box lid is marked ‘Paris Exhibition 1867, George Davidson, U.S. Coast and Geodetic Survey Philadelphia, Pa’.  It has a 10-inch radius frame, and the catalog listing indicates that it is marked “U.S. Navy 30183”.  A close-up view of the limb in a catalog photo is not sharp, but I can see that the number 30183 is preceded by the Naval Observatory ‘NO’ hallmark and followed by an ‘RO’ symbol.

George Davidson U.S. C&G.S. Sextant

A fourth sextant, which is currently listed as for sale in the online catalog of another antiques dealer [6], has 'Captain Walton O. Hooker Jr Gardiner Maine Ship “Harry Morse" 1878' marked in script on its index arm and on a plate on the the sextant’s box.  The catalog listing indicates that the limb is marked 'E. Loueux a Paris (2266)  Schiaveni Bellieni a Bresl', and 'US Navy R31518'; a close-up view of the limb reveals the latter marking to be US Navy followed by an ‘RO’ symbol and the number 31518.  Attached to the inside of this sextant’s box lid is a U.S. Navy inspection certificate dated October 10, 1918, indicating that it was classified as a high grade sextant.  I have found nothing confirming that a sextant maker or dealer of by name Loueux existed, and so I’ve wondered if this sextant was actually made by Lorieux, a French instrument maker in the 19th century.

Captain Hooker Sextant and Box

Box Handle Anchor Plate, Captain Hooker Sextant

Limb Markings on the Captain Hooker Sextant

The fifth sextant is an octant with an eight-inch radius brass frame with an ivory arc scale that was listed in an online auction held in 2010 [7].  The octant is described as being marked ‘US Navy 13126’, and the box that holds it is said to contain a label for D. Eggert & Son, a marine chronometer maker and seller of nautical instruments in 19th century New York City [8].  From what little I know of D. Eggert & Son, they were not sextant makers, thus it is unclear who this sextant’s manufacturer was. The auction listing does not mention an ‘RO’ symbol, but I think it likely based on the examples of the four previous sextants that an ‘RO’ symbol  precedes the ‘13126’.

D. Eggert & Son Sextant

I didn’t doubt that the markings scratched into the limbs of these five sextant were put there by the U.S. Naval Observatory, but why were they different than the usual Naval Observatory markings?  What was the ‘RO’ symbol in place of the usual Naval Observatory hallmark meant to signify, and why were the serial numbers following the ‘RO’ symbol five digits long, not four digits or less?

The five sextants were not only different in terms of how the Naval Observatory marked them, they were very different kinds of sextants than the ones the U.S. Navy typically acquired in the early 20th century.  At least four of the five sextants were made by non- U.S. sextant makers, and the frame radius and bracing pattern of several of them don’t conform with the U.S. Navy sextant specifications.  All five sextants appear to have been made in the 19th century and so they are older than any of the sextants whose limbs are marked with NO serial numbers.  Several of them appear to have been in the possession of private citizens (the Captain Gifford and Captain Hooker sextants) or a civilian government entity (the George Davidson Coast & Geodetic Survey sextant).  Many sextants with the usual ‘NO’ number markings ended up in the hands of private citizens or civilian organizations after they left U.S. Navy service, but it seemed quite possible that these three sextants were used by civilians before they entered U.S. Navy service.  So, my guess was that the OR serial number system was used by the U.S. Navy to track non-standard sextants that it had acquired in some way other than its usual acquisition process, which I understand to have been to purchase sextants made to U.S. Navy specifications from the manufacturer that offered them at the best price through a competitive bidding process [9].

At first I had no idea how or why the Navy might have come to possess these five sextants, but then I remembered something I had read about in the Annual Reports of the U.S. Naval Observatory.  When the United States entered into the First World War, U.S. manufacturers were unable to meet the demand for many kinds of nautical instruments needed by the Navy and merchant marine fleet.  U.S. Navy Assistant Secretary Franklin Delano Roosevelt therefore led a campaign to solicit the public for donations of nautical equipment [10].  The campaign was publicized with Eyes for the Navy posters like the one below, which emphasized the need for binoculars and spyglasses to help the crews of naval vessels and merchant ships look for German submarines.

Eyes For the Navy Poster

Binoculars and spyglasses were not the only kinds of equipment the Navy asked the public to donate, however.  An organization called The Four Minute Men, which sent speakers into theaters throughout the country to give short speeches urging the public to donate nautical equipment to the Navy.  An internal memo circulated by the organization to help its members prepare their speeches contains a statement from the Navy about what equipment was needed and how donated items would be handled [11]:

"Send your binoculars, spyglasses, and telescopes by parcel post or express to Franklin D. Roosevelt, Assistant Secretary of the Navy, care of Naval Observatory, Washington, D. C. (Sextants and chronometers are also urgently needed). On the outside of the package write your name and address. On the inside, tie a tag on the instrument, again giving your name and address.
Immediately upon receipt you will get a letter from the Naval Observatory, stating that a test will be made.

Instruments are tested as soon as possible and those not suitable are returned to the sender. So far, only 5 per cent have been found unsuitable. Instruments somewhat out of repair will be accepted as there is a repair department in the Naval Observatory. A glass with a slight chip may pass the test, but the glasses must be of a good grade.

Upon acceptance of the glass, sextant or chronometer, you will be sent a letter of thanks, signed by Franklin D. Roosevelt, Assistant Secretary of the Navy. A check for $1 will be sent you, which sum will constitute the rental price, or in event of loss, the purchase price of the article.

The instrument is then entered in the records at the Naval Observatory with your name, address, and key number. A metal tag with your name and address is securely attached by wire to the instrument and, as an additional safeguard, your key number is engraved on the inside of the instrument. The instruments are then shipped in lots and distributed among the commandants who in turn distribute them, taking a receipt for each instrument, just as is done with all other Navy property.

While it is, of course, impossible to guarantee your glass, sextant or chronometer, against damage or loss, every precaution has been taken for its return at the close of the war. The only precaution the sender needs to take is to notify the Naval Observatory of any change of address, or to see that mail being sent to the old address will be properly forwarded at the close of the war."

Things to note here are that sextants were among the items that the public was being asked to donate; that donated items were sent to Franklin D. Roosevelt, c/o the U.S. Naval Observatory, where they were inspected for usability; and, that Naval Observatory engraved a ‘key number’ on equipment accepted for use.  It’s tempting to think that the ‘R’ in the ‘RO’ symbol on the five sextants signifies that they were donated by civilians through the program led by a man whose last name begins with the letter ‘R’; the Naval Observatory’s Annual Report for Fiscal Year 1919 refers to the donated equipment as “Roosevelt Glasses”, which suggests that at the Naval Observatory, Roosevelt was very much associated with the donated equipment.  The Fiscal Year 1919 Annual Report states that some 52,000 donated binocular and spyglasses had been received and inspected at the Naval Observatory, of which some 32,000 had been accepted for use.  A serial number series extending to five digits would have been needed to track that number of donated equipment [12].

In another part of the memo, the organization’s director wrote the following about what the Eyes for the Navy campaign had already achieved by the February, 1918 date of the memo:

“Many remarkable binoculars, spyglasses, telescopes, chronometers, and sextants have been received. Among these are many that have historic interest dating back to the Spanish, Civil, and Mexican Wars, even the War of 1812, and a few from the Revolution— these glasses have already done their bit. They are coming to the Navy now for use in this greatest of all wars; they are coming from men of science, from travelers, from sportsmen, from men who have had a good glass lying idle for years and years.

Who will want to keep a glass for a little selfish amusement when it can serve such a serious and such a great purpose? Who will dare appear in public with a glass, after the Navy needs are known.

Wm. McCormick Blair, Director, Four Minute Men”

This confirms that sextants were indeed among the items the U.S. Navy received through the Eyes for the Navy program.  Perhaps the Gifford, Hooker, and Davidson sextants were the kind of things Blair was referring to in his comment on the age and historical interest of some of the donated nautical equipment.
 
So, a pretty strong circumstantial case can be built around the idea that the five sextants were donated to the U.S. Navy through the Eyes for the Navy campaign.  This idea provides a plausible explanation for the NR symbols and the five-digit serial numbers they are marked with, and why the Navy had in its possession sextants that weren’t American-made to U.S. Navy specifications (i.e., civilians were under no obligation to buy sextants made to government specifications).  What I had missed until a couple of weeks ago was that I had in my possession a piece of evidence that makes this case rather definitive.  While trying to put my collection of sextant photos into better order, I happened to take a look at a photo of the side of the box for the George Davidson sextant displayed at the Paris Exhibition of 1867.  That photo,reproduced below, shows a shipping label indicating that the box was sent by T.D. Davidson of San Francisco, California to  ‘Hon. F.D. Roosevelt, Naval Observatory, Washington D.C.’, i.e., the address to which the Eyes for the Navy campaign instructed the public to send donated nautical equipment.

Shipping Label on the George Davidson Sextant Box

Comments, corrections, additional relevant facts, differing viewpoints, etc., are always welcome.  Send to gardnersghost@gmail.com
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Footnotes
[1] A photo of this sextant box can be seen at the TIGHAR web site.  Go to https://tighar.org/wiki/Sextant_box_found_on_Nikumaroro.  I suspect that this sextant box may date to the very late 19th century.
[2] This according to the catalog description of a very similar-looking sextant in the Smithsonian Museum’s Behring collection.  See: http://amhistory.si.edu/navigation/object.cfm?recordnumber=1059152
[3] The New Bedford Whaling Museum’s online catalog of its holdings can be found at: https://www.whalingmuseum.org/explore/collections/database
The RO symbol is described as a registered trademark symbol in a museum catalog pdf file I downloded at:  https://www.whalingmuseum.org/sites/default/files/Navigational-Instruments-Catalogue.pdf
[4] This according to a web page of the Smithsonian Museum’s Behring Center: http://amhistory.si.edu/navigation/maker.cfm?makerid=99.  Earlier and later in the 19th century, Spencer, Browning & Co operated under similar names.
[5]  Skinner Auctions online catalog: https://www.skinnerinc.com/auctions/2684M/lots/641
[6] Rock Island Auction Company online catalog: https://www.rockislandauction.com/detail/60/1470/cased-antique-naval-observatory-sextant-with-accessories
[7] Skinner Auction online catalog: http://www.skinnerinc.com/auctions/2502/lots/521
[8] A history of the firm Eggert & Son can be found on pages 375-376 of: Marine Chronometers at Greenwich: A Catalogue of Marine Chronometers at the National Maritime Museum, Greenwich (Oxford University Press).  This book can be read online at Google Books.
[9] A competitive bidding process involving sealed bids is referred to in an October 10, 1917 article in  Jeweler’s Circular Weekly.  A copy of that article can be seen in an earlier post titled “What to the Numbers 3500 and 1542 Tell Us? Part Three”.  How the sextant acquisition process worked at the turn of the 19th Century is described in the Department of Nautical Instruments section of the Report of the Superintendent of the United States Naval Observatory dated July 1, 1898: 
“The purchase of sextants by award of contract to the lowest bidder was so far modified to invite instrument makers to submit sextants made in accordance with careful specifications, the contract to be awarded at a stated price to the maker whose work showed the highest accuracy and perfection of work. Four firms submitted a sample of sextant of the two classes called for (a high-grade sextant at $100 and a surveying sextant at $90), with the exception of Warner & Swasey, who submitted only s high-grade sextant.  As a result of the competition, the contract for the high-grade sextant was awarded to Warner & Swasey, of Cleveland, Ohio, and for the surveying sextant to F.E. Brandis, Sons & Co of Brooklyn, N.Y.”
[10] Page 8 of the U.S. Naval Observatory’s Annual Report for Fiscal Year 1918 reports on a ‘drive for glasses’ overseen by Assistant Navy Secretary Roosevelt.  Page 6 of the report explains that at the outset of the war, American manufacturers were unable to produce needed items at a sufficient pace, and that the production of optical glass at a sufficient rate to meet needs was a particular problem.
[11] A copy of the Four Minute Men memo can be viewed in the digital collection of the University of Colorado at Boulder: http://cudl.colorado.edu/luna/servlet/detail/UCBOULDERCB1~58~58~426219~124520:Eyes-for-the-Navy
[12] The numbers stated in the report would seem to be rounded to the nearest thousands; while the numbers are said to be for ‘glasses’, I suspect that they are for all types of equipment.  The serial number of the Captain Hooker sextant, RO 31518, is the highest of the five sextants discussed here, looks to be close to the end of the RO serial number series.

Brandis Sextant Taxonomy, Part Six: U.S. Navy Sextant Specifications

Brandis Catalog No. 20, which I’ve referred to in several earlier posts, tells us about a few key features of four different Brandis sextant types.  A great deal more information about three of these sextant types can be found in the sextant specifications that were published from time to time by the U. S. Navy.  The Navy began publishing specifications for sextants in the 1890s with the aim of improving the quality of the sextants produced for it by instrument manufacturers.  As explained in the Department of Nautical Instruments section of the U. S. Naval Observatory’s Annual Report for fiscal year 1895 [1]:

“The province of this department is to receive, inspect, and issue to the vessels of the Navy all instruments (chronometers and watches excepted) furnished for navigating and surveying purposes.
In order to put this important service upon a proper basis and to assure its systematic working whereby the best instruments can be obtained, detailed specifications have been prepared with great care for sextants, high-grade and surveying; octants; binocular glasses, day and night; quartermaster’s spyglasses, high, medium, and low power; officer-of-the-deck spyglasses; barometers, mercurial and aneroid; clocks, deck and boat; three-arm protractors, and theodolites.

A complete outfit of the apparatus necessary to the thorough inspection of instruments has been provided for and will soon be installed for use. Contractors have experienced some difficulties in fulfilling the requirements of the specifications, but better progress in that direction is now being made, and by rigidly enforcing the specifications our ships are being supplied with instruments of the above classes uniform in pattern and excellent in quality.”

I have copies of the U.S. Navy’s surveying sextant specifications published in 1897 and 1901, its high grade sextant specifications published in 1897, and its specifications for octants published in 1900 [2].  Each of these documents is four pages long and consists of a series of numbered sections stipulating the features of a particular sextant component or accessory.  The sextant features described in Brandis Catalog No. 20 match up well with those put forth in the specifications, even though Brandis Catalog No. 20 was published about 15 years after these specifications appeared [3].  For example, the catalog listing for the “U.S. Navy Surveying Sextant” states that it has a 6-inch radius and reads to 30 seconds of arc, while the 1901 surveying sextant specifications requires a frame radius not less than 5.75 inches nor more than 6.0 inches and a vernier scale providing a reading precision of 30 seconds of arc; the catalog listing for the ‘U.S. Navy High Grade Sextant’ states that it has a 7-inch radius and is readable to 10 seconds of arc, while the 1897 high grade sextant specifications require a frame radius between 7 and 7.5 inches and a vernier scale providing a 10 second reading precision; the catalog listing for the ‘U.S. Navy Octant’ states that it has a 7-inch radius and is readable to 30 seconds of arc, while the 1900 octant specifications require a frame radius between 7 and 7.5 inches and a vernier scale providing a 30-second reading precision.

Something I find curious about the Navy surveying sextant specifications is that they require surveying sextant frames to have four radial arms “stiffened by one transverse brace, which shall be an arc of a circle concentric with the limb”.  The ‘U.S. Navy Surveying Sextant’ illustrated in Brandis Catalogue No. 20 (see illustration below) has the required curved transverse stiffener brace, but it also has a second, straight, transverse stiffener brace, and I’ve seen many Brandis surveying sextants made for the Navy that have this frame pattern.  I’ve also seen surveying sextants made for the U.S. Navy by two other U.S. manufacturers, Keuffel & Esser, and Buff & Buff, that have two transverse braces, although these surveying sextants have two curved transverse stiffener braces [4].  It seems that these three sextant manufacturers believed that two transverse braces were needed to give their Navy surveying sextant frames sufficient stiffness, so then why is it that the Navy surveying sextant specifications required only one transverse brace?

There are only a few differences between the surveying sextant specifications published in 1901 and those published in 1897.  One such difference is in the specification for the tangent screw used to make fine positional adjustments to the sextant’s index arm.  The 1897 specifications call for a single-headed, 4.1-inch long, tangent screw, while the 1901 specifications call for a two-headed, 2.75-inch long, tangent screw.  This arcane difference is of interest to me because I’ve collected photos of dozens of Brandis sextants that I’ve found on eBay and other web sites, and many of these photos provide a good view of the sextant’s tangent screw.  When I went through my photo collection I was able to clearly identify twenty-two of them to be surveying sextants [5].  Of these twenty-two surveying sextants, only the oldest of them, Brandis serial number 1899 [6], has a long, single-headed, tangent screw.  The rest of them, spanning a range of Brandis serial numbers from 2539 to 5675, have a short, two-headed tangent screw (see table and photos below).

Brandis Surveying Sextant Serial Numbers and Tangent Screw Types

Brandis #1899

Brandis #2539

Brandis #5675

If it is assumed that Brandis manufactured these sextants to U.S. Navy specifications [7], then Brandis #1899 must have been made no later than 1901, the year that surveying sextant specifications calling for the shorter tangent screw was published [8].  The ‘no later than’ date for the manufacture of Brandis #1899 provides an additional reference point for the Brandis serial number chronology that was presented in ‘What do the Numbers 3500 and 1542 Tell Us? Part Two’.  Some time in the not-too-distant future I will post a revised version of the Brandis serial number chronology that will include the reference point provided by Brandis #1899 as well some others I’ve arrived at since that chronology appeared.

If there is a master list of all U.S. Navy sextant specifications ever published, I have not seen it, but I do know that the four specifications I have copies of aren’t the only ones ever published.  According to the National Directory of Commodity Specifications [9], the Navy published surveying sextant specifications in 1912 and high grade sextant specifications in 1914.  An article in the July 24, 1918 issue of the trade journal  Jeweler’s Circular Weekly, which is reproduced in the post titled ‘What do the Numbers 3500 and 1542 Tell Us? Part Three’ reports the recent publication of Navy surveying sextant specifications and states that these new specifications supersede those published in 1912.  I know that octant specifications were published in 1895, because my copy of the 1900 octant specifications ends with the statement “Reprint of May 20, 1895. No change”.  I have not found any indication of the existence of specifications for either of the other two Brandis sextant types discussed in earlier posts, the astronomical sextant listed in Brandis Catalog No. 20, or the Brandis sextant with the 5-inch radius frame whose name I am uncertain of.

I would like to have copies of all the U.S. Navy sextant specifications ever published.  If I knew what changes the 1918 surveying sextant specifications called for relative to 1912 specifications, I might be able to find where in my collection of Brandis sextant photos those changes first appear and so add another dating reference point to the Brandis serial number chronology.  If the Navy published specifications for the 5-inch sextant type whose name I am uncertain of, I’d have a definitive name for this sextant type.  There are some specific changes I’d expect to see in versions of the sextant specifications that published after the ones I have copies of.  For instance, each of the four sextant specifications I have copies of require that sextants be supplied to the Navy in sextant boxes having a brass plate sunk into the top of their lids.  The purpose of this plate is made clear in the octant specifications, which states that the manufacturer was to mark the plate with the sextant’s Naval Observatory number, the Naval Observatory hallmark (the letter ’N’ inscribed with the letter ‘O’), and the words ‘U.S. Navy’ upon acceptance of the sextant by the Navy.  I’ve seen these plates in the lids of Brandis sextant boxes made before World War One (see photo below), but not in the lids of Brandis sextant boxes made during World War One and so I suspect that the specifications in effect during the war no longer required them; it would be nice to to read those specifications to see if this is in fact true.

Box Plaque for Brandis 2763/USNO 348, an Octant

I’ve looked at sextants made by two of Brandis’ U.S. competitors to see how well they match up with the Navy specifications, but I’m not sure I can quickly summarize what I found so I’ll save that discussion for another post.  I’ll end this post by repeating something I may have mentioned in an earlier post, and that is that I’ve seen a few Brandis sextants that don’t match any of the sextant types listed in Brandis Catalog No. 20.  Some of these sextants have features that don’t jibe with the specifications that I have copies of.  This too is something that requires more than a brief discussion, and so I will save it for a future  post.
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UPDATE (12/17/2017):
Having written only two days ago that Brandis #1899 is the only surveying sextant I’ve seen that has a long, single-headed tangent screw, this morning I came upon a second Brandis surveying sextant, Brandis #1839, with this type of tangent screw. The Brandis serial number and ‘U.S. Navy’ is stamped into the arc, as per a few other old Brandis sextants, and the front of the box is marked ‘Sur Sex 1839’.  A scrap of a Naval Observatory certificate remains, enough to see first two digits of the Brandis serial number and the letters ‘Su’ on the line for sextant type.  See photos and updated table below.

Comments, corrections, additional relevant facts, differing viewpoints, etc., are always welcome.  Send to gardnersghost@gmail.com
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Footnotes
[1] Report of the Superintendent of the U.S. Naval Observatory for the Year Ending June 30, 1895.  Washington.  U.S. Government Printing Office, 1896. Page 116.
[2] These four sextant specifications were copied onto microfiche by the Congressional Information Service and are available at libraries around the United States. U.S. Executive Branch Documents, 1789-1909; numbers N-507a -241,-269,-270, and -271.
[3] See the post titled ‘A Brief Note on the Date of Publication of Brandis Catalogue No. 20’ published on February 16, 2017.
[4] The frame pattern of Keuffel & Esser and Buff & Buff surveying sextants, however, differs from Brandis surveying sextant in that both transverse braces are curved.  The K&E and B&B sextants I refer to here have Naval Observatory inspection certificates identifying them as surveying sextants.
[5] I determined each sextant to be surveying sextant if it’s frame had one straight and one curved stiffening brace and at least on of the following was true: there was a Naval Observatory inspection certificate for the sextant identifying it to be a surveying sextant, or the sextant’s arc scale was divided in 20 minute intervals.  Both cases were often true. 
[6] Brandis #1899 is not marked with  U.S. Naval Observatory serial number but we can be sure it was once in U. S. Navy service because ‘U.S. Navy’ is stamped into its limb, as can be seen in the photo of this sextant in this post. 
[7] Note that most of these sextants in Table 1 have a U.S. Naval Observatory serial number, indicating they were inspected to Navy specifications at the Naval Observatory.  Note also that Brandis Cat No. 20, which was aimed at the civilian market, calls its surveying sextant a ‘U.S. Navy Surveying Sextant’, which suggests to me that even the surveying sextant that Brandis sold to civilians were made to Navy specifications.
[8]  Most of the sextants in Table 1 were made during World War One, thus if Brandis manufactured them to U.S. Navy specifications, then the Navy surveying sextant specifications in effect during World War One must have required the short, two-headed tangent screw.
[9] National Directory of Commodity Specifications. National Bureau of Standards U.S. Government Printing Office, 1925. Page 289. This can be found online at Google Books.

A Brief Note on the Date of Publication of Brandis Catalogue No. 20

I’ve previously noted that Brandis Catalogue No. 20, which is not dated, contains a testimonial letter from a customer dated December 12, 1914, and so we know the earliest that it could have been published was some time in 1915 [1].  Up until a couple of days ago my best guess for the latest date that it could have been published was sometime in 1917.  That ‘no later than’ date was based on the presence of the ‘Brandis & Sons Mfg. Co’ firm name on the catalog’s front page.  If the Brandis firm name was changed from ‘Brandis & Sons Mfg. Co’ to ‘Brandis & Sons, Inc.’ sometime in 1917 as I've previously suggested [1], then Brandis Catalogue No. 20 must have been published sometime between early 1915 and the end of 1917.
 
I can now shave about a year and a half from that ‘no later than’ date.  A few days ago I came across volume 181 of the Journal of the Franklin Institute [2], which lists Brandis Catalogue Number 20 as a gift to the Franklin Institute’s library.  Volume 181 covers the period from January to June of 1916, and so the date range for the publication of Brandis Catalogue No. 20 is narrowed down to sometime between early 1915 and June of 1916.

Although I can’t prove it, I suspect that Brandis Catalog No. 20 was published in the first half of 1916.  I think that in early 1916 Brandis was giving away copies of its newly-published Catalogue No. 20 to technically-oriented institutions around the country, and the Franklin Institute was a recipient of one of these free catalogs.  As support for this idea, I note that the John Crerar Library in Chicago, another technically-oriented institution, lists "Brandis & Sons Mfg. Co." as the donor of an unspecified ‘volume or pamphlet’ in its annual report for calendar year 1916 [3].

The date of publication of Brandis Catalog No. 20 is a fairly arcane matter, but I felt it was worth this brief note because this catalog tells us exactly what four types of Brandis sextant looked like at a particular period of time.  Pinning down just when that particular period of time was as well as we possibly can doesn’t seem like such a bad idea.

Comments, corrections, additional relevant facts, differing viewpoints, etc., are always welcome (no one will be banned, blocked, or castigated for offering differing opinions).  Send to gardnersghost@gmail.com 
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References/Footnotes
[1] See footnote 1 of ‘A Brandis Sextant Taxonomy, Part Five - Five Inch Radius Sextants’.
[2] Journal of the Franklin Institute, Volume 181, No. 6, June 1916.  page 864.  This can be downloaded at Google Books.
[3] The John Crerar Library Twenty Second Annual Report for the Year 1916, page 34.  This can be downloaded at Google Books.

Brandis Sextant Taxonomy, Part Five - Five Inch Radius Sextants

Brandis 3249, which was the subject of the post titled ‘A Strange Beast’, is an example of a fifth type of sextant that Brandis and Sons was making in the early twentieth century.  It has a frame with a 5-inch radius, two radial arms, and a single curved stiffener brace.  Its arc scale is divided in 30 minute intervals and it can be read to a precision of 1 minute with the vernier scale on its index arm.  Unlike the four sextant types discussed in previous posts in this series, sextants like Brandis 3249 do not appear in Brandis Catalog No. 20 [1].

Brandis 3249

Brandis 3249 was the first example of a sextant of this size and frame pattern that I came across, but I’ve seen several more of them since then.  Some, like Brandis 3249, are equipped with a pinhole sight and shade glass selector wheel, while others, like Brandis 3692 and Brandis 3738, are equipped with a sighting tube or a telescope.  Brandis 3692 and Brandis 3738 are equipped with a set of index shades, which are standard components of the four types of Brandis sextants discussed in previous posts in this series, however they lack the set of horizon shades that are also standard components of these other four sextant types.  The sextant in the photograph below, reproduced from a Carnegie Institution report on early experiments in aerial navigation [2], has yet another configuration of optical components.  It has a pinhole sight like Brandis 3249, but rather than having a shade glass selector wheel, this sextant has the arrangement of shade glasses seen on Brandis 3738 and Brandis 3692, i.e., it has a set of index shades but no horizon shades. I have not seen a surviving example of a sextant with this particular configuration of optical components.

Brandis 3738

Brandis 3692

Carnegie Report Sextant

The caption of the photo in the Carnegie report states that this sextant is a “Patrol-boat-type sextant, with 5-inch arc”, and a section of the report titled ‘Report of November 13, 1918 on Progress Since October 1 in Developing Astronomical Methods for Determining Geographic Positions of Airplanes on Long Flights’ provides the following additional details:

“At the United States Naval Observatory a small patrol-boat-type sextant (see Pl. 14, Fig. 4) was inspected. This sextant had just been completed for the Navy Department by Brandis and Sons, Brooklyn, and it appeared that it could very easily be adapted for airplane use. The arc has a radius of 5 inches and is graduated to half degrees up to 180. The loan of this instrument has been obtained from the Navy Department for experimental use in airplanes. It is understood, if the instrument is found satisfactory, that there are 150 of the same type being completed which can be turned over to the Army at once.”

I’m tempted to call any 5-inch radius Brandis sextant a patrol boat sextant, regardless of its optical components, but this might be an oversimplification.  For one thing, if you look at the interior of the boxes that Brandis 3249 and Brandis 3692 are stored in, you’ll see that neither sextant box is made to hold the optical components of the other.  The user of Brandis 3249 couldn’t remove the pinhole sight and shade glass selector and replace them with index shades and a telescope to convert to the configuration seen on Brandis 3692, or vice versa; neither sextant was supplied with the components needed to do so [3].  For the same reason, neither Brandis 3249 nor Brandis 3692 could be converted into the sextant in the Carnegie report photograph.  Since these three sextants aren’t interconvertible it seems possible that they were considered to be three different sextant types, each with their own names, back at the time Brandis was making them.  An additional wrinkle is that I’ve found two more names that seem to have been associated with 5-inch radius Brandis sextants.  One name appears in the December 1919 issue of the nautical magazine Rudder.  An article on page 14 reports:

“Brandis & Sons, Inc. of 754 Lexington Ave., Brooklyn, N.Y., have issued their new catalog, showing the four styles of sextants they build. The Navigational sextant is 7 1/2 inches and sells for $130—the largest size they make; the six-inch sextant sells for $105; the ‘Mates’ sextant sells for $80, and the baby of the line, developed for small-boat work, has a 5-inch radius, complete in every detail and sells for $60. If you are interested in sextants built for and by Americans, send for their descriptive catalog. All Brandis’ sextants are built to Navy standards.”

A Brandis advertisement on page 8 of this same issue (this advertisement was reproduced in ‘What do the Numbers 3500 and 1542 Tell Us? Part Two’) gives ‘high grade’, ‘surveying’, ‘mates’, and ‘motor boat’ as the names of four types of sextants that Brandis was then producing, and so it would seem that the ‘motor boat sextant’ referred to here is the “baby of the line” described on page 14.  The other name appears in the article in the February 1920 issue of Marine Review that was reproduced in full in ‘What do the Numbers 3500 and 1542 Tell Us? Part Three’.  The relevant section reads:

“Aside from the type of sextant illustrated, the company manufactures a 6-inch sextant, similar to the 71/2-inch sextant with the exception that the arc is 6 inches; a mate’s sextant, which is a simple instrument, and a power boat sextant designed as a compact unit for use in coastwise work.”  

The company referred to here is Brandis and Sons, and what is written in Marine Review article so closely parallels the information published just a few months earlier in The Rudder that I think we can be pretty sure that ‘power boat sextant’ and ‘motor boat sextant’ refer to the same instrument.  No photographs or illustrations of the power boat/motor boat sextants are provided, so what optical components they were configured with is unclear.  I wonder if the term ‘power boat sextant’ is a misnomer introduced by the author of the Marine Review article rather than an actual Brandis product name (see update at bottom of post). If ‘patrol boat sextant’ was in fact the general name for all 5-inch radius Brandis sextants when they were being produced during the first World War, perhaps the name ‘motor boat sextant’ was cooked up as a more civilian-friendly name to sell these 5-inch sextants to recreational boaters after the war.

Moving on from terminology to functionality, the arrangement of shade glasses in these 5-inch sextants suggests to me that they were intended for a different purpose than the four Brandis sextant types discussed in previous posts in this series, all of which were intended primarily for celestial navigation.  As mentioned above, all four of those other Brandis sextant types are equipped with both index shades and horizon shades.  The index shades are used when taking sun sights to reduce the brightness of the image of the sun reflected by the index mirror, while the horizon shades are used to properly view the horizon when it is obscured by glare or haze.  Sextant users taking sun sights will often need very dark index shades to view the sun properly, but they will often only a lightly tinted shade or no shade glass at all to properly view the horizon.  Sextants with the two sets of shade glasses thus allow users to independently adjust their view of sun and horizon so that both can be properly seen in order to take a sun sight.  Sextant users attempting to take a sun sight with a sextant like Brandis 3249 would have to view both the sun and the horizon through the same shade glass, and I would think they would frequently find themselves unable to do so because the dark shade needed to view the sun would render the horizon impossible to discern.  Since taking sun sights was a common task for a celestial navigator at sea, a sextant that often couldn’t be used to take sun sights would have been of limited use for deepwater navigators.

While we tend to think of sextants as instruments for measuring vertical angles of celestial bodies for celestial navigation, they can also be used to measure horizontal angles between landmarks for coastal navigation, and I think that this is what these 5-inch sextants were primarily intended for.  Sextant users measuring angles between landmarks along a coastline would rarely need to simultaneously view two objects of greatly different brightness as often happens taking a sun sight, and so there would be fewer problems using sextants with just one shade glass set.  I note that sounding sextants, which are specifically intended for measuring horizontal angles between surveying markers when conducting hydrographic surveys, may have no shade glasses at all [4], and that there are examples of sounding sextants using a pinhole sight as a viewing device [5].  So, to return to the subject of terminology, one could reasonably call a sextant like Brandis 3249 a sounding sextant (and since sounding sextants are also called hydrographic sextants, we now have five names for these 5-inch Brandis sextants).  Further support for the idea that these 5-inch sextants were intended for measuring horizontal angles comes from the three names I found for them, all of which suggest instruments that are intended for use on vessels operating close to shore.  Remember also that the Marine Review article states that what it called power boat sextants were used “in coastwise work”, which I think can reasonably be taken to mean for coastal navigation.

So if shade glasses aren’t essential for measuring horizontal angles, why were some of these 5-inch sextants given a set of index shades?  My guess is that while these sextants were primarily intended to be used for coastal navigation, they were given index shades to make them more versatile celestial navigation instruments--the index shades made it possible to take sun sights with them.  But then, why not go all the way and give them set of horizon shades as well?  I don’t have a good answer to this question; perhaps the horizon shades were omitted to make them a little less expensive, but I would think the cost savings resulting from such a design choice would be pretty small.

There are a few things worth noting about the boxes in which Brandis 3738 and Brandis 3657 are stored.  First, both boxes are marked with serial numbers of other sextants; the box that Brandis 3738 now resides in is marked with Brandis serial number 3268, while Brandis 3692 now resides in a box marked with Brandis serial number 3657; these serial numbers can be seen stamped into the underside of each box lid close to a box hinge in the upper right hand corner in the photos above.  This tells us that the 5-inch sextants these boxes originally held, Brandis 3268 and Brandis 3657, must have been equipped with either a telescope or sighting tube since that is what their boxes are designed to hold.  Also, an unusual feature of both boxes is that they have numbers stenciled on their exteriors (seen photos below).  The box for Brandis 3268 (which now holds Brandis 3738) has the number ‘882’ stenciled onto it, and the box for Brandis 3657 (which now holds Brandis 3692) has ‘883’ stenciled on it [6]. What is the significance of the numbers 882 and 883?  My guess is that these are the U.S Naval Observatory serial numbers of the sextants these boxes originally held.  The numbers 882 and 883 are in the same general ballpark as the Naval Observatory numbers of the other Brandis 5-inch sextants I’ve come across as can be seen in the table below.

Brandis #     USNO #    Comments
   3227             845         Pinhole sight and shade glass wheel; still in original box; this sextant is
                                       is in the collection of the Maritime Museum.
   3239             850         Pinhole sight and shade glass selector; auctioned on Invaluable.com web site.
   3249             836         Pinhole sight and shade glass wheel; still in original box.
   3268             882?       Box only; box has holder for sighting tube or telescope; Number ‘882’
                                       is stenciled on exterior of box.
   3657             883?       Box only; box has holder for sighting tube/telescope; Number ‘883’
                                       stenciled on exterior of box
   3692             N/A         Now in box originally holding Brandis 3657; box now contains a telescope.
                                       Auctioned on eBay.  Seller did not  report a USNO number.
   3738             945         Now in box originally holding Brandis 3268 Sextant box now contains
                                       a sighting tube.

While I’ve been able to shed some light on these 5-inch radius Brandis sextants, these sextants remain somewhat mysterious and in need of further research.  I suspect that reliable sources exist somewhere out there that will clarify basic issues such as how these sextants were named.  I’ll keep on looking for those sources and will report back anything I manage to turn up.  If anyone out there in my vast readership can help provide clarity on these somewhat mysterious sextants, please do drop me a line.

Update 2/16/17:  Reader C.V. has found a Brandis advertisement referring to Power Boat sextants on page 12 of the June 1930 issue of Motor Boating magazine (this can be found using Google Books), so 'Power Boat Sextant' is not a misnomer.  Reader C.V. feels that 'patrol boat sextant' is the odd term out as it is found only in the Carnegie report while multiple instances of the other two names for this sextant type appear in post-war sources.

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[1] Brandis Catalogue No. 20 is undated, however is contains a testimonial letter from a customer dated December 12, 1914, so the earliest it could have been published was some time in 1915.  The firm name on the front page is ‘Brandis & Sons Mfg. Co.’; in the post titled ‘What Do the Numbers 3500 and 1542 Mean? Part Three’ I concluded that that some time in 1917 the firm name changed to ‘Brandis & Sons, Inc.’.  Therefore, Brandis Catalogue No. 20  must have been printed some time between 1915 and 1917.
[2] J.P. Ault, Navigation of Aircraft by Astronomical Methods, in: Ocean and Magnetic Observations, 1915-1921 Carnegie Institution of Washington, Publication 175, vol. 5. Washington, D.C. (1926)  Available at Google Books?
[3] An additional reason these sextants are incompatible is that even if a user somehow got a hold of a set index shades it wouldn’t be possible to attach the frame of Brandis 3249 without drilling anchoring holes into the frame.
[4] See for instance: https://sextantbook.com/2009/04/26/sounding-sextants-1/
[5] An illustration of a sounding sextant with a pinhole sight can be found in S.K. Duggal,  Surveying, Volume 2,  Page 146.  Tata-McGraw-Hill Education, 2004 (viewable online at Google books); Bill Morris also mentions that some sounding sextants were equipped with pinhole sights in reference [4].
[6] These two sextant boxes and the sextants that were in them were auctioned on eBay within a few weeks of each other by two different sellers in Illinois.  One of these sellers told me he was unaware of the auction of the other sextant and sextant box.