73 
On a New Form of Actinometer. 
By H. C. Russet, B.A., F.R.A.S. 
[Read before the Royal Society of N.S.W., 5 November, 1884.] 
Amoncst the instruments designed to record the sunshine, I have 
not seen one which satisfied the conditions required, viz., an instru- 
ment that would not only record the hours of sunshine, but mea- 
sure and record the heat received on a given surface in a given 
tim i 
arms attached to the cross-head of the polar axis and parallel to it 
would move above this half-cylinder and at the same distance from 
it throughout the day. The use of these arms is to carry a light 
pen-carriag 1y tingonthe paper which is attached tothe half 
cylinder. Attached to the upper end of the polar axis is a frame 
supporting a short-focus 12-inch lens, so arranged that its axis for 
adjustment in declination would, if continuous, pass through the 
& miniature water-boiler and supply it with water from a 
reservoir attached to the stand, the supply going in at the bottom 
and the steam out of the top ; the water in the boiler will therefore 
be at a practically constant height and supplied at a temperature 
known by a thermometer placed in the “eagle which is pro- 
en the 
Triage, caus : 
amount of water evaporated, and may in a very hot day make it 
move the whole length of the slide, 9 inches. 
