292 REPORT OF COMMISSIONER OF FISH AND FISHERIES. 
world. Her equipment is especially complete, and she is provided 
with convenient and ample laboratory facilities for the study and 
preservation of specimens. 
Running diagonally across the section from the circular aisle of the 
rotunda was a display of the common forms of apparatus employed in 
marine investigation. The beam trawl which was spread on the floor 
is the most efficient apparatus for gathering specimens from the bottom 
of the ocean, and has been used by the Adbatross in a depth of 4,200 
fathoms, about 44 miles. Hanging to the frame above the trawl were 
several appliances used in collecting from the surface, bottom, and 
intermediate depths. The tangle, which, as its name indicates, entangles 
specimens in its hemp or manila swabs, is used where the bottom is 
so rough and foul that trawls and other forms of nets would be torn 
or otherwise seriously damaged. The Chester dredge, with its hooks, 
is used to catch worm-like animals and certain species of mollusks 
which habitually burrow in the mud of the bottom. The ordinary 
dredges are used from very small boats in shallow water, or from the 
steamers when, for some reason, it is impracticable to use the beam 
trawl. They not only scrape up animals lying on the bottom, but 
also dig up organisms which burrow but slightly. 
In all of the apparatus used for bottom collecting, the contents are 
emptied into a series of sieves on the deck of the vessel, and after 
being washed, to remove the mud and sand, are carefully assorted and 
the specimens placed in suitable reagents, usually alcohol, and pre- 
served for study in tanks, bottles, and other receptacles. 
The large surface tow net, which is lined with even-mesh silk bolting- 
cloth, is used in collecting the wealth of life swarming on the surface 
of the water. The surface or pelagic life, much of which is minute, is 
extremely important to the fisheries, as it supplies, directly or indirectly, 
the food for most of the denizens of sea and lake. 
In the study of life at intermediate depths the open net is unsuitable, 
as it catches specimens while it is being hauled to the surface, and 
the depth at which a given specimen is eaught is indeterminate. ‘To 
obviate this difficulty and to enable the investigator to determine with 
accuracy the depth from which his specimen came, two forms of net 
are employed by the Fish Commission. They are towed at the depth 
which it is desired to study, and before being: hauled in are closed by 
a messenger or weight which slides down the wire rope by which they 
are towed and actuates a device connected with the frame of the net. 
Draped on the frame over the trawl and otherwise disposed about the 
section were seines, gill nets, scoop nets, scrape nets, and other apparatus 
used in making shore collections of fishes and other organisms. 
The collecting tanks and chests in which specimens are preserved 
and transported were shown by the side of the trawl, and adjacent to 
them was a Tanner sounding machine, with its accessory apparatus 
for obtaining the bottom temperature and specimens of the bottom 
