62 An Improved Self-Registering Ram- Gauge. 



Siemens' machines have given the greatest amount of effi- 

 ciency. For subdividing the light, the Jablochkoff s}^stem, 

 certainly, has had the greatest success; but the new Siemens 

 machine should be capable of doing quite as much work. 

 At present the Siemens and the Gramme appear to be ahead 

 of any other system, and have, therefore, been adopted most 

 extensively. 



I have not in this paper attempted to enter into any 

 details with respect to the economy of any system, or its 

 relative value as compared with ordinary means of illumina- 

 tion. 



The results of experiments I shall shortly be engaged in 

 will, I hope, enable me to lay before you some information 

 on this part of the subject. 



Art. IX. — An Improved Ombrograph, or Self-registering 



Rain- Gauge. 



By K. L. J. Ellery, F.R.S., F.RA.S. 



[Read September 9th, 1880.] 



On the 16th May, 1878, I gave a description of a new self- 

 registering rain-gauge that I had devised, which appears 

 at page 2 of Vol. XV. of our Transactions, accompanied by a 

 rough diagram of the arrangement. This apparatus has 

 been in use at the Observatory ever since, and, with the ex- 

 ception of an occasional failure of the intermittent syphon 

 by which it empties itself immediately a quarter of an inch 

 of rain has fallen, it has always worked very satisfactorily. 

 It, however, became apparent to me that it was open to con- 

 siderable improvement in one or two particulars, which I 

 think I have now succeeded in accomplishing. It will be 

 remembered that the instrument referred to consisted of a 

 receiving vase suspended by two well-made steel spiral 

 springs about five inches long and three-quarters of an inch 

 in diameter. Into this vase the rain as collected in the 

 rain-gauge flowed, the springs stretching as the vase de- 

 scended with the increasing weight of the collected water 



