Page 63
C O M P A S S N E E D L E
1 A compass in a mahogany box.
2 A compass needle and apparatus to investigate the inclination of the needle,
by Nairne and Blunt of London, being completely the same as the apparatus
used by the Captains Phipps and Cook to investigate the dip of needles during
their travels in the north.
3 Compass with sights and Nonius-indicator, being the so-called Landmeeters
Bousole by W. Kenrick.
Page 64
A T T R A C T I V E F O R C E [ C A P I L L A R I T Y ]
1 Two inverted syphons, with a wide and a narrow limb of glass, set against
small planks on small bases, to show the attraction between water and glass
and the repulsion between mercury and glass, ’s Gravesande, III, fig. 5.
2 Two flat-glasses, in a small trough, to show the rising of liquids between the
same, ’s Gravesande, III, fig. 4.
■f 3 Two flat mirror-glasses, the separation regulated more or less by a screw, to
observe the rising or falling of a drop of oil between them, ’s Gravesande, I,
fig. 4.
Page 65
O P T I C S
Apparatus for the refraction of light rays
1 The heliostat o f ’s Gravesande, LXXXIII.
f 2 The apparatus to allow a ray of light to travel between 2 knife-edges and observe
their bending, ’s Gravesande, LXXXVI, fig. 2, 3.
3 The complete’s Gravesandian refraction apparatus as it is illustrated, plates
LXXXVI I & LXXXVIII.
f 4 A glass cube of 2! inches, ’s Gravesande, LXXXVII.
]■ 5 A glass cube of 2 inches.
t 6 A cube of Iceland crystal [spar] of 2-\- inches, very pure.
f 7 A small, square, glass trough, to be filled with liquid.
8 A glass with many polished facets, in a brass tube or so-called anamorphus-
viewer.
Page 66
O P T I C S
Apparatus for the separation of light-rays and colours
1 A glass prism, placed horizontally in a small cabinet, ’s Gravesande, CX,
fig. I 8.
2 A prism placed vertically in a similar small cabinet.
t 3 An apparatus in which 2 prisms can be placed above one another, ’s Gravesande,
CXIV, fig. 1.
4 A double prism on a small base, ’s Gravesande, CXIV, fig. 1 [should read fig.
3, 4-]-
5 Three rectangular hollow upright prisms, to be filled with liquids, ’s Gravesande,
CXI, fig. 4, and CCVI, fig. 1.
6 Three similar, of which one has equal sides and two others different sides,
with an apparatus and base to place them horizontally.
7 A brass plate and apparatus on a base, to suspend in it small prisms and let
the light rays fall on them. With this:
8 coloured prisms
3 equal-sided prisms
3 unequal-sided prisms
1 prism of Iceland crystal [spar].
Page 67
A P PA R A TU S FOR R E FR A C T IO N
1 Four coloured plates fitting over one another at an angle, set in a brass frame,
to show the mixing of colours.
2 A prismatic glass ring on a small base.
3 A similar ring of Iceland crystal [spar], in a mahogany box, with it a stand
on which this ring can be placed.
4 A glass cone on a base.
5 A glass cone, which gives a double refraction of light-rays, which is caused by
a separation or layer set round the axis, and a brass tube, which can be
screwed in the brass plate described on the previous page.
6 A cone of Iceland crystal [spar], in a similar brass tube, which can be screwed
on the same plate.
7 An arrangement of small prisms of crown-glass and flint-glass, to show how
by the combination of the different sorts of glass the colour dispersion is
produced, by Dollond.
f 8 Two somewhat convex glasses, which by 3 screws can be pressed on to one
another to show coloured rings, ’s Gravesande, CXX, fig. 2.
Page 68
A P P A R A TU S FOR CO N CA V E AND CO N V E X LENSES
1 Two convex lenses [collectif glazen\ of different focal lengths on small stands,
’s Gravesande, C, fig. 4.
]■ 2 A convex lens of ... inches focal length, set in wood, on a stand.
3 A c o n v e x l e n s o f 8 f in c h e s d i a m e t e r a n d 2 - f o o t f o c a l l e n g t h , o n a s t a n d .
4 A very pure rock crystal ball \kogel\ set in a brass tube, which can be screwed
in to the brass plate No. ... after the apparatus for the prisms has been removed,
marked No. 1.
5 A clear glass ball [kogel] cut through the centre, set in a similar brass tube,
No. 2.
6 A very convex lens in a brass ring, No. 3.
7 A convex lens in a brass ring, No. 4.
8 A convex lens, on the one side flat, being 4 of a ball, No. 5.
9 A convex lens, on the one side very convex, on the other side a little concave,
No. 6.
10 A double concave lens, No. 7.
11 A lens on the one side concave, on the other side flat, No. 8.
These 8 lenses are all in the same mahogany chest in which are the prisms.
Page 69
MICROSCOPES
f i Two microscopes (the one of silver and the other of brass) of Leeuwenhoek, in
a small brass box.
2 A simple and a double microscope by Adams, illustrated in his Microscopical
Essays, plate —
3 The lucernal microscope by Adams for opaque and transparent objects,
illustrated in his Microscopical Essays, plate — With this also a lantern and
lamp to project shadows of the objects on a paper screen. The lenses, small
apparatus and objects for the same in a small mahogany chest.
4 A solar microscope by ... in a small shagreen case.
5 A small box with objects: the sections of wood are made in London; the remainder
by Ypelaar.
6 An apparatus to make very thin section of wood for the microscope.