106 FRANK C. WILSON 



B, at Ci and the finely drawn-out glass tube at C 2 . When the 

 apparatus has been lowered to a desired depth, a small brass 

 messenger, A, is sent down on the connecting line of the sampler. 

 It strikes the lever arm at d and the force is transmitted to the 

 constricted glass tube at C 2 , which is broken against the break- 

 ing pin, E, and the vacuum destroyed. The sample tube fills 

 rapidly. 



The sample tubes are ordinary 2.5 by 20 cm. (100 cc. volume) 

 hard glass test tubes, fitted with a one-hole rubber stopper. A 

 small glass tube bent at a right angle is inserted in the opening 

 in the stopper. The lower end of the glass tube should project 

 through the rubber stopper about half an inch. The other end 

 is heated and drawn out at a certain point, the point being de- 

 termined by the size of the holder, to a diameter of about 2 mm. 

 so that it may be sealed easily. It is best, of course, to draw out 

 the tube before inserting it in the stopper. The sample tube to- 

 gether with the rubber stopper containing the small glass tube is 

 sterilized in the autoclave. When sufficiently cool, the stoppers 

 should be fitted tightly into the tubes. If the same stoppers are 

 used repeatedly, they should be coated with a mixture of rosin 

 and paraffin after they are sterilized to prevent loss of vacuum. 

 A partial vacuum is produced in the tubes by attaching the filling 

 tube to a vacuum pump. The tube is sealed at the constriction 

 by a flame at the time the air is being exhausted. It is preferable 

 to have only a partial vacuum in the sample tube so that it will 

 not fill entirely with water, as the space left in this way permits 

 the shaking of the water sample before the dilutions are made. 



This type of sampler offers several advantages. The tubes 

 are easily and quickly clamped in the frame. They fill quickly 

 when the tip of the filling tube is broken off. The rapidity of 

 operation is shown by the fact that it requires only about ten 

 minutes to draw samples of water from seven different depths — 

 at the surface, 1, 5, 10, 15, 20, and 23 meters. There is no spe- 

 cial container required for carrying the samples to the laboratory 

 as they are left in the same tubes in which they are collected. 

 The operation of placing the tubes in the frame may be carried 

 out without touching the tips of the filling tubes with the hands, 



