548 Wisconsin Academy of Sciences, Arts, and Letters. 
together by springs and there was a positive release not unlike 
that of the Petterson bottle. This bottle has been described by 
Dr. Kemmerer in his report to the Bureau of Fisheries. 
The Survey needed in 1918 another bottle and one was devised 
and made by Mr. J. P. Foerst, mechanician of the department of 
physics, University of Wisconsin. It resembles the Kemmerer 
bottle in using a brass tube and rubber stoppers, but differs in 
employing gravity instead of springs to bring the parts together 
and in using a friction release instead of a catch. 
The tube, or bottle proper, is 43 cm. long and 6.7 cm. (2.5 in.) 
in diameter and holds about 1400 cc. Through its center extends 
a small tube 56 cm. long, on which the movable parts slide. The 
suspension line is passed through this tube and is knotted below 
it. When the parts of the bottle are separated, the upper stop¬ 
per is held in place by two small pins which are pressed by springs 
into a shallow groove near the top of the small inner tube. The 
larger tube when raised is held in a similar way by pins attached 
to one of the two wheel-like guides inside the large tube. These 
guides keep the large tube centered on the small one and so con¬ 
trol its descent to the lower stopper. 
The ends of the tube are ordinary rubber stoppers. Each is 
held between two brass discs screwed together, so that the stop¬ 
per can be easily removed when it becomes hard. A short, heavy 
brass cylinder is attached to the top of the upper stopper in 
order to give it more weight and so to make sure that it will re¬ 
lease the large tube and cause the bottle to close. Through each 
stopper passes a small tube on one side; this ends in a rubber 
tube closed by a spring clip. The lower tube serves to allow the 
water to flow from the bottle; the upper one serves to admit air 
as the water flows out. 
On the top of the whole apparatus when in use there is placed 
a rubber stopper to receive the blow of the messenger and to pre¬ 
vent this from battering the brass of the tube or the stopper. 
The operation of the bottle and the method of release are plain 
from the figures. 
Such a bottle operates very satisfactorily. We have found 
it simpler than the original Kemmerer bottle and equally satisfac¬ 
tory. It can not take the place of more elaborate bottles for 
certain types of investigation, but it is entirely adequate for most 
purposes of lake studies. It is convenient, light, and inexpensive, 
