545 PRISMS (334,339,340,389) 3/4 19th C.
334 45° prism mounted in brass with a pin to attach on mahogany
stand, with tightening screw. Prism 48 x 48 x 68; overall height
339 t^ i P/nSm °n braSS Stand; enSraved on Prism support: Duboscq
Soled H Paris. Leaded base 110 diameter; height of stand to
knurled screw 265. Length of prism in brass holder -147.
340 60° prism ■ brass stand; engraved on prism support: Duboscq
Soled 4 Pans. Leaded base and height of stand as 339. Prism
length same.
389 Prism pair on brass stand; engraved on prism support: Duboscq
4 Pans. Diameter of leaded base 95, height of stand as in p h o lg
graph 330. Below prism support is a brass bar with a hole in the
rounded end, length 155. Glass 60° prisms height 25, sides 21.
■
546 LIQUID PRISMS (337, 338, 765, 766, 767, 8 9 || 1871/1885
337 Glass bottle cut so that two flat glass sheets may be cemented
to it to form a 60° liquid prism. Diameter 59, overall height 82.
338 Two triangular liquid prisms set in black-brass frames.
1. With ground glass stopper; edges measure 65.
2. With two holes, no stopper; edges measure 60 x 60 x 55.
Three bottle prisms (height of each to stopper 105) in cartons of black
546' (765, 766, 767) card. The card round each prism has the origin written in white ink by
Jsttf338/l-2, 892)>'>v: the museum staff. The records show that all were purchased in 1885.
765 John Browning London 1871
H k >6 Wm. Albert in Frankfurt 1871
| | ! | 6.7 , Wilh” Albert Frankfurt 1871
892 Small liquid prism (35 x 35 x 25) set in blackened brass with
brass stopper and two sides of triangle of brass with circular
— glass windows.
•m M PRISMS AND LENS If64> 7 6 9 * 6 ) 1885
■64
1169
EH
Liquid 45° prism formed from glass bottle in brass mount
-(height 651« Mounted on stand with cast iron base (diameter
110). Height to knurled screw 245. Stamped in oval:
J. DUBOSCQ A PARIS. Museum records give dale as 1885
for all three in this group.
Biconvex lens in wooden frame, focal length 13.5. Diameter of
frame 127; diameter of visible portion of lens 92. On stand
with leaded base (diameter 109); height to top of knurled
screw 262.
HPrism in shape of a trapezium (length 7W mounted in cork in
a cylinder at the middle of a large black disc (diameter 145) .
"The disc bears the makers oval stamp: J. DUBOSCQ A
PARIS. Prism to Amici’s pattern. Brass pillar with base weighted
with iron (diameter 110). Height to knurled screw 267.
547 (769, 764.1111
548 PRISM & LENS: ROCK CRYSTAL (759, 760) 1886
SignecfeJS DjffcRETET & C” A PARIS
Base diameter 78; overall height to top of dome: 1®
Both elements have glass domes sealed into black-painted brass bases.
Signature 011 760.
■ 5 5 Contains equiangular prism: of rock crystal, set on cork,
Length of prism 35, side 20.
760 A brass mounting holding brass ring containing a biconvex
lens of rock crystal, diameter 35. On one side is a circle of cork
with a central hole, distorted.