NORTHWESTERN LAKES OF THE UNITED STATES. 
57 
telescopes closely over the pipe ( C ). These tubes pass 
through guides in the main tube (A) , and the latter is sup- 
ported, when the apparatus is open, by a screw in ( D ) below 
the upper guide. The stoppers are drawn together by springs 
(7) made of No. 16 phosphor-bronze wire. They are held 
open by a double catch attached to the upper stopper that 
locks over the bushing (if) on the central tube ( C ). This 
catch is. opened by a messenger ( L ) that is dropped down 
the line ( B ). The f-inch brass pipe (K) is notched to rest 
on the catch and allows the tube ( 0) to rise without hitting 
the messenger. The sampler is fastened to the line by a 
knot below the spring (J). G is a ^g-inch brass tube to 
which a piece of rubber tubing is attached and serves as an 
air vent when drawing the sample from the tube (H ) . Both 
are closed by pinchcocks when the sampler is lowered. 
The apparatus may be taken apart for cleaning by 
unhooking the springs, removing the bushing ( M ), and 
turning the top stopper so that the screw in D passes 
through the notch in the opposite side of the guide. The 
rubber stoppers may be replaced by removing the nuts 
that bind them to the tubes. 
SAMPLING LINE. 
During the summer of 1911 cash carrier cord (which is 
similar to No. 5 window cord) was used for taking samples. 
This was obtained in 1,000-foot lengths, and when saturated 
with paraffin it made a fairly satisfactory line. For the 
latter part of the work a •^-inch linen bluefish line was used. 
This was saturated with melted paraffin, stretched, dried, 
and calibrated in meters. These calibrations were later 
checked with a wire sounding machine under working con- 
ditions and found to be accurate to about 1 per cent. 
BOTTLES. 
The samples were taken in 250 cc. pop bottles, which 
were loaned by the Wisconsin Geological and Natural His- 
tory Survey. These bottles have snap stoppers so ar- 
ranged that only rubber comes in contact with the water 
or solution. The stoppers are easily closed, leaving no 
air bubbles in the bottle, and put the water under a slight 
pressure. The bottles have numbers ground on the side, 
and the volume of each bottle is recorded with the num- 
ber. They are carried in light wooden cases containing 
16 squares in which the bottles fit. The bottles were 
Fig. 3. Deep-water sampler. A, main tube; B, line; C, central tube; D, telescopic tube; E, rubber stoppers; 
mechanism; G, air vent; S’, sample tube; J, springs; J , open spring; K, brass pipe; X, messenger; M, 
H- 
