Featured Nautical ?? Engraving - book plate?

I bought this in the church sale from Heaven on Saturday. A friend was buying a stack of prints, probably from a dealer's stash of broken up books, and I snagged this one. The only information included is that it was an engraving from circa 1790. It's on laid paper and has a nice plate mark, so I'm guessing that bit is on the money. The nautical part is my guess. It looks like some sort of navigation aid, a deck grate, and some rope. Beyond that...no clue.

 

Looks like some kind of sextant.

 

It matches up better with an octant, from what I can google.

 

Or maybe a theodolite, possibly astronomical depending on the size of the scope.

 

Perhaps an hydrographic circle, but the one at this link was invented in the19th C.

http://www.etesseract.com/Navigation/Navigationimages/hurl1b.jpg

 

Nice!!!!

 

It was too cool to pass up. I made a friend's son, he's an engineer, buy some astronomy diagrams. We were both geeking out on them, and this one came home with me instead. What the book was that it came in...not a clue.

 

Possibly a pelorus.

https://en.wikipedia.org/wiki/Pelorus_(instrument)

 

Text accompanying picture I linked above

THE HYDROGRAPHIC CIRCLE OF ROLLET DE L'ISLE, French, late 19th century, finely signed "Lorieux, A. Hurlimann, Succ'r a Paris." The 10-1/2" (27 cm) diameter brass circle is fitted with four mirrors, two of them mounted on the rotating index arm and set back-to-back at a fixed angle, a large-light-gathering-power telescope, and a hinged turned wood handle. An inset circular scale is divided every 0.5 from -10 to +200 half-degrees. The index arm has clamp, fine motion tangent screw, vernier to one-fiftieth of a degree, and magnifier. The instrument is equipped with its full complement of accessories, all original: two solar filters, two right angle sights, seven interchangeable filters, two adjusting tools, three spare mirrors, fitted mahogany case 13" (33 cm) square, and key. Only the screwdriver and loupe are lacking. Condition is absolutely superb throughout. The circle functions basically as a sextant, except there are two "horizon" mirrors, and two "index" mirrors, disposed so that one pair is useful at smaller angles, the other pair at larger ones. Readings are possible from 0 degrees straight ahead all the way to 180 degrees directly behind the observer -- as one mirror view becomes foreshortened, the other takes over automatically.

This is the remarkable invention of M. Rollet de l'Isle, French hydrographic engineer to the Marine (and world-famous proponent of the Esperanto language). It was still advertised in 1911 (by Ponthus & Therrode, successors to Hurlimann, who in turn was successor to the well-known firm of Lorieux established in 1845), as the model adopted by the French hydrographic marine services. A very rare example of this innovative design, in splendid condition. (8194) $7200.

 

May be a thing called a Borda Circle (developed in the 1780s).
https://www.google.com/search?q=bor...y_DXAhUhc98KHRI7AasQ_AUICigB&biw=1102&bih=619

(Lots of stuff in this thread I've never heard of before.)

*********
Check reflecting circle instruments and geodetic survey instruments.
This may be for land based surveying and intended for use in a horizontal position.

There's a similar type of engraving currently listed on eBay
https://www.ebay.com/itm/EDWARD-TRO...IFIC-TOOL-PATENT-ENGRAVING-1832-/141431053053

 

Hmmm. It's definitely similar. I think this is a Cercle de Borda or Borda's Repeating Circle. I found one from the 1790s that's about dead on. http://www.cordouan.culture.fr/accessible/en/uc/03_03_01-Borda and Lenoir’s device for Cordouan

 

Ok looks like Borda Circle people (not me, sniff,) are the winners! Pretty clear, two mirrors on two arms, a precision vernier screw on each arm, telescope, graduated circle, that’s it!

 

Just don't ask me to use one.

 

Oh please????

 

I get "seasick" in the front seat of my mother's Chevy.(LOL) It's the angle of the windscreen or something.

 

I'm learning a lot from the image discussion. Thanks!

 

If you compare the drawings in op’s pix to those in MOS’s Eboo link, the Eboo item’s fig. 2 is for all practical purposes identical to OP’s, just lacking as much detail. So maybe OP really has


EARLY SCIENTIFIC
INSTRUMENT INVENTION
EDWARD TROUGHTON
ALTITUDE CIRCLE SCIENTIFIC
GEODETIC SURVEYING TOOL
ANTIQUE GRAPHIC ILLUSTRATED
EDINBURGH ENCYCLOPEDIA
ENGRAVING PRINT
1832

 

"windscreen" !!!
~
We don't have those in the US.

 

I've been ODing on BBC2 reruns on Youtube lately.

 

The angle of the dangle leads to the illusion of the confusion. - mhh