1-20 E X P L A N A T I O N OF THE T A B L E S ,
G, 'A large common canal or veftiblcj by which the three femicircular canals
communicate.
H, A bag which communicates with the veftible at I.
K, A ftonc taken out of the bag H, reprefented of its natural fize, and likewife
magnified.
T A B L E X L * .
F i g . I.
THIS Figure reprefcnts an horizontal fedion of the cryftalline lenfes of an
Ox and of a Cod enlarged to four diameters; one-tenth part of an inch in the
figure reprefenting one-fortieth part of an inch in thefe lenfes.
A B C D, The lens of the Cod.
E , The middle of the greateft diameter of the lenfes.
F A , The radius of the anterior part of the lens of the cod B A C .
N.B. Filiould have been placed at the twentieth of an inch from E.
E D, The radius of the pofterior convexity of the lens of the cod.
I L , The greateft tranfverfe diameter of the lem ot the OY.
I K L , The anterior convexity of tlie lens of the ox.
G K, The radius by which the anterior convexity of the lens of the ox was
defcribed.
I M L , The pofterior convexity of the lens of the ox.
HM, The radius of the pofterior convexity of the lens of the ox.
I i L m , A dotted figure, reprefenting the feclion of a lens of the breadth of
that of the ox, and defcribed with fuch radii as Dr Petit afligns to the fpheres
which compofc the lens of the ox.
F i g . 2.
A B C D , Reprefcnts the fection of a hollow fphere of glafs, ¿/its centre.
F, The focus of parallel rays of light, after being tranfmitted through fuch
a fphere filled with water.
KhccI , A lens, formed of the anterior and pofterior portions of the fame
hollow fphere j the length of the axis of which is equal to the radius of the
fphere.
D, The focus of parallel rays, after they have paifed through fuch a lens
filled with water.
Aidk, The fecbion of a lens; the breadth of which is exactly equal to the
diame-
U