On Abyssinian Tube Wells. 5 



swept away * M. Elie de Beaumont advanced the theory that 

 sand-dunes might serve as natural chronometers, by which 

 the date of the existing continents may be ascertained ; that 

 by observing the rate at which the particles of sand travel, 

 we may calculate the period when the movement commenced. + 

 Sir C. Lyell, however, doubts the correctness of this theory, 

 observing that " this test must be applied with great caution, 

 so variable is the rate at which sand may advance into the 

 interior.^: 



Art. V. — On Abyssinian Tube Wells. 

 By Francis Corbett, Esq. 



[Read 13th July, 1874.] 



These pumps were constructed of six lengths of ordinary 

 iron piping for gas pipes, each of six feet long. Into one of 

 these lengths was screwed a piece of solid iron, pointed, about 

 eight inches long, and the shoulder next the pipe was made 

 of a greater diameter than the pipe. This is for driving 

 into the ground, and the diameter being greater than the 

 pipe, it clears the way, especially where the holes are made 

 in the pipe. Just above where this solid point is screwed, 

 holes are drilled in the pipe for the water to enter, just as in 

 any ordinary tubing for a well, for sixteen or eighteen 

 inches in length. The number of these holes must of course 

 be in proportion to the size of the pump, so as to admit as 

 much water as the pump is capable of throwing. Less holes 

 would be required in a small pump, suitable either for 

 domestic purposes, or for a small paddock. The pumps I 

 got Mr. Danks to adapt the pipes for were No. 6 Douglas, 

 the largest size made by that manufacturer. They are as large 

 as can be reasonably worked by manual labour, and the 

 larger the pump the better, as it takes the man less time to 

 fill the troughs. Mr. Danks' arrangement for attaching the 

 different lengths of the piping to one another is very good, 

 as the pipes preserve their full strength. He has a ring or 

 hoop about three inches broad, tapped from both ends, with 

 right and left handed internal screws. The ends of the 

 pipes have screw threads worked on the outside of them, 



* Principles of Geology, 1867, L, p. 513. 



t Geologie Pratique, p. 218. 



| Principles of Geology, 1867, i., p. 516. 



