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| Brandis 3249 |
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| Brandis 3738 |
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| Brandis 3692 |
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| 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.
