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This lauiu'li, built by the Racine Boat Mauufafturiug' Company, of Racine, 

 "Wisconsin, is 2') t'eet long by (i foot beam and is licensed to carry seventeen 

 persons. The machinery fm-nished with it was replaced during the summer 

 by a compound engine of four and a half horse power, with keel condenser. 

 Both boiler and engine were designed by Assistant Professor VanDervoort 

 of the University department of nu'chanical engineering and the engine and 

 the speed propeller wei-e made under his direction at the University shops. 

 The launch was not designed especially for speed, the distances to be covered 

 in our work being usuallj' very short. It gives us, however, a rate of about 

 six miles per hour. It is entirely safe in all weathers to whicli it may be ex- 

 posed in our situation — a point of special importance to us since our regular 

 I'outine of field work must be carried oiit without reference to storm or tem- 

 perature. Four skiffs of various sizes and a portable canvass boat complete 

 the aquatic equipment. 



The more peculiar items of the field and laboratory apparatus are the 

 plankton equipment, the breeding cages for the aquatic insects, and a specially 

 constructed centrifugal machine for the rapid precipitation and condensation 

 in graduated tubes of the product of quantitative collections. This last is 

 a modification of the centrifuge used by physicians, the tubes and tube car- 

 riers being the same, but the mechanism being- specially designed for us by 

 Proressor VanDervoort and made under his supervision at the University 

 shops. The plankton apparatus first used consisted of a peculiar conical net 

 (Apstein pattern) made of No. 20 silk bolting cloth. This was hauled through 

 the water obliquely from bottom to top, a distance of thirty metres, 

 at a perfectly imiform rate, the movement being timed by seconds counted 

 with watch in hand. The net was suspended to a carrier and drawn along a 

 tightly stretched line, to which it was hung by means of pulleys, the various 

 particulars of the arrangement being devised by Assistant Professor Smith, 

 in charge of the plankton apparatus and the Station itself during the first 

 year. Tn May, 1896, this plankton net was superseded by a hand force- 

 pump, selected after considerable investigation of various styles, of a size 

 and weight to be conveniently managed in a lai'ge skiff. The feed pipe 

 of this pump is long enough to I'each the bottom in our deepest water and 

 the discharge pipe delivers into a straining net suspended in the water fi'om 

 a float to secure the contents of a vertical section. The further end of the 

 feed pipe is sunk to the bottom and slowly raised to the surface, the pump 

 being meanwhile worked by an assistant in a perfectly regular manner. 

 Minor features of the apparatus and items of the procedure will be described 

 in a special paper on our Station methods, now in course of preparation by 

 the Station Superintendent. 



For keeping insect larvae under perfectly natural conditions but exposed to 

 continiial observation small cubical boxes were used, with two sides and the 

 bottom of wood and the other two sides of wire gauze, and a cover of glass 

 set in a wooden frame which overhung the top 'of the case, fitting closely to 

 the sides. These cases wei-e placed around a large float in the lake or river in 

 such a manner as to be kept about half full of water, which ofcourse had free 

 access through the wire gauze sides. 



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