FRESH-WATER MARLS. 345 



In boring, the handle should be twisted around as the rod is shoved 

 down, even though the surface material may be soft enough to permit 

 it to be driven down without twisting, because if the latter method is 

 adopted the surface material first taken up by the auger will cling to 

 it during its descent, and will prevent securing a sample of the marl 

 at lower depth. As each new length of pipe is added, the couplings 

 should be firmly tightened, as neglect of this precaution may mean 

 the loss of most of the outfit through uncoupling while it is being 

 drawn up. 



This device gives good results when employed on a fairly dense marl 

 not deeply covered by peat or grass, because the auger will clear itself 

 of the surface material on the way down and will retain fairly well the 

 clean sample taken at the bottom. 



In heavily covered marl-beds, or in dealing with very fluid marls, 

 other boring devices must be tried. A clumsy but efficient type of 

 sampler for this purpose is made as follows: Take a 2-foot length of 

 1-inch gas-pipe and thread one end for coupling. Screw reducers on the 

 coupled end until the last reducer can take a frinch or ^-inch pipe, 

 any necessary number of lengths of which pipe will form the rod proper. 

 Sharpen the open edge of the 1-inch pipe and fit into it a plug with a 

 shoulder that fits against the rim, allowing the plug to penetrate ^ inch 

 into the open end of the pipe. Sharpen the end of the plug opposite 

 the shoulder and bore a hole lengthwise through the plug. Pass a 

 A-inch iron rod through the plug from the shoulder end and bolt it by 

 screwing a nut upon the end opposite the shoulder, which end should be 

 sharpened so as to penetrate the marl more easily. The end of the rod 

 may be threaded for several inches and a nut screwed on, then pass the 

 end of the rod through the plug and screw the nut tight against the plug. 

 This will hold the plug in place during boring 'and withdrawing. The 

 rod is inserted in the 1-inch pipe and passed up through that and the 

 f-inch pipe, from the upper end of which the free end of the rod may 

 project. The rod gives a means of either closing firmly or opening the 

 bottom end of the 1-inch pipe. When boring, the plug is held firmly 

 against the mouth of the pipe by means of the rod, and the whole appara- 

 tus is shoved down into the marl to the desired depth. The pipe is then 

 raised, while the rod is held stationary; the apparatus is held in this 

 position a moment to allow the marl to close in about the rod and then 

 the pipe is lowered until the plug closes it. With the plug held firmly 

 the entire apparatus is raised to the surface, the plug loosened, and the 

 sample of marl taken out of the section of 1-inch pipe. This device can 

 be driven through and withdrawn from a marl-bed covered by peat, 



