204: Memo, on the subject of Rain Gauyes. [no. 2, new series, 
all, a heavy fall of rain, the receiving vessel must be a large one, 
if the Funnel diameter is 12 inches. No ordinary bottle (which is 
the cleanest and best receptacle) will do, and the consequence is a 
chatty is used, which is porous, easily broken and awkward to pour 
from into a narrow cylinder. 
The second objection is, that the Register is not intelligible 
generally to those who keep it, and the orders of the Board that 
the Registers are to be sent to them to reduce " Measures," " Inches" 
and " Tenths," give the idea, that the inches and tenths, are inches 
and tenths fall of rain which is not the case. It will also be seen 
that the reductions are tedious when they come to extend over se- 
veral Reports. Every " measure" has t6 be multiplied by 5, every 
inch by -0625, and every " tenth" by " '00625. 
Now I venture to suggest a form of Rain Gauge which will re- 
gister accurately to 100th of an inch fall of rain, and which will be 
free from every objection urged against the present one. The Fun- 
nel is 4-97 inches in diameter, and its area is therefore, 17'33 
square inches, therefore a fall of rain of one inch, is 17'33 cubic 
inches in the reservoir, which is simply a common quart bottle. 
The rain water is poured out of the bottle into a little tin vessel 
holding one fluid ounce, and each of these full denotes that jV of 
an inch of rain has fallen. A stick notched to a 10th of the depth 
of the little cylinder, will show how many tenths of water there are 
in the said cylinder, and each of these is equivalent to ji^ of an 
inch of rain, though for country work, a lOth of an inch (each cylin- 
der full being yV of an inch) may be sufficient. 
The diameter of the Funnel, is theoretically, 4 697 inches ; but 
in practice, 4-65 is found sufficient. This is a little smaller than 
the theoretical diameter, because it is impossible to expect Native 
workmen to bend the mouth of a tin funnel, to a true cylinder. 
The tin funnel is much cheaper than a copper one. 
A wooden Gauge might be sent from Madras to each Cutcherry, 
to which the funnel might be fitted. 
The quart bottle is more convenient than a chatty or earthern 
ware pot, and is quite large enough to suit any fall of rain in the 
Carnatic. It will run oyer if the fall is above D| inches, but this 
