ON EARTH XKEMORS. 



297 



ment of the cellar is taken up for a few inches round the drain-pipe. A 

 wooden plate, e, covers the drain-pipe without touching it, and rests 

 only on the cellar floor. 



Angular Value of Scale •divisions. — The pendulum was erected bv Mr. 



Fig. 5. 



3 



O O O 



o o o 



o o o 



o o o 



o o o 



c C o 



o o 



o 



^a!;^-^'/^ 



Horace Darwin on April 20 and 21. Experiments were made to deter- 

 mine the angular value of the scale-divisions at various times between 

 May 1 and 25, and again between August 1 and 3. The first trials were 

 unsatisfactory, the image seldom returning to the same or nearly the 

 same position. Some of the causes of failure were easily remedied ; but 



