454 
lowing plan was adopted. Thick glass tubes, nar- 
rowed at the ends, and closed by an enamelling-lamp 
after a vacuum had been previously formed, were at- 
tached to the metallic tube enclosing the thermome- 
ters. They were arranged in such a manner, that, 
when the overthrow of the latter took place, one of 
their slender ends struck the lower part of the metal- 
lic frame bearing the thermometer. Under this shock 
the point struck broke, and then the water rushed 
into the interior of the tubes, from which it could not 
make its escape on account of the small diameter of 
the entrance. At each sounding, therefore, a speci- 
SCIENCE. 
[Vou. IIL, No. 62. 
during the night, it was possible to search with great 
care for the smallest objects brought up. For this 
purpose, a. Gramme machine was placed upon the 
bridge, and was connected with a set of Edison lamps, 
lighting either the trawl.or the interior of the lab- 
oratory. The lamps on the bridge were supplied 
with a reflector, allowing a bright light to be thrown 
upon the sea. Thus the approach of the trawl to 
the surface could be easily watched. 
The Edison lamps used to light the ship were also 
useful, by floating in the water, in attracting fishes 
into the nets previously arranged. 
One can imagine 
Fic. 12.— Effect of expansion on the air-bladder of a fish taken from a depth of fifteen hundred metres. 
men of the water at the bottom was brought up; and 
it was very easy to preserve this by immediately seal- 
ing the tube. 
Dredging at great depths requires considerable time, 
so that it often happens that the trawl can be brought 
on board only very late in the day. In the tropics 
night comes on early, the twilight in these regions be- 
ing of short duration. To overcome this important 
difficulty, care was taken, while equipping the Talis- 
man, to arrange electric apparatus capable of furnish- 
ing light so bright, that, when the trawl] was raised 
the beauty of the scene when these brilliant lights 
are lowered into the water. The surrounding sea is 
illuminated with @azzling and constantly changing 
rays. It seems as if one were watching beautiful 
medusae, which, like bright disks, rise and fall with 
the waves, turn and disappear, to rise again a few 
minutes later more sparkling than ever. 
Contrary to expectation, the deep-sea fish brought 
to the surface are somewhat affected by the expan- 
sion they have experienced. Many fishes possess a 
peculiar organ, consisting of a closed sac situated 
