322 Nine Inch Conical Rain Gage. 
_ ofthecone. Three inches fall of rain will then fillsuch a cone. Since 
the contents of similar cones are as the cube roots of their heights, 
in order to-make a scale for measuring the rain fallen into such a cone, 
obtain the cube roots of 30 numbers, proceeding arithmetically from 
one, for the tenths of the three inches severally, and multiply each . 
cube root by such a number as, being multiplied into the cube root 
of 30, shall give 9. That number is found to be 2.9. This will 
give 4.18, for three tenths of an inch; If then the 30 cube roots be 
multiplied by such a number as, when multiplied into the cube root 
of 30, will give 4.18, they will give the divisions of the scale for hun- 
dredths of the three first tenths of an inch. This multiplier is found 
' to be 1.345, very nearly. 
According to these rules the following table is constructed. 
I. Il. 1. EVE Ll. Il. Vil. VV. 
Sa aye! 2.90 | 1.345 16 | 2.521 | 7.30 | 3.39 
2 | 1.260 | 3.65 | 1.69 17 | 2.571 | 7.45 | 3.46 
Zs 49 WANS OF 18 | 2.621 | 7.60 | 3.53 
441 °1.5687-| 460+) 2943 19 | 2.668 | 7.74 | 3.59 
5 | 1.710 | 4.96 | 2.30 20 | 2.714 | 7.87 | 3.65 
64 LBL) 5.37 .2.44 21 | 2.759 | 8. ou 
We 1.913'| 5.55 | 2.5%, 22 | 2.802 | 8.12 | 3.77 
8 | 2. 5.80 | 2.69 23 | 2.844 | 8.24 | 3.83 
9 | 2.080 | 6.03 | 2.80 24 | 2.885 | 8.36 | 3.88 
10 | 2.154 | 6.25 | -2.90 25 | 2.924 | 8.48 | 3.93 
11 | 2.224 | 6.45 | 3. 26 | 2.962 | 8.59 | 3.98 
12 | 2.290 | 6.64 | 3.08 27 | 3. 8.70 | 4.03 
1312-252 al O.82) | ead 28 | 3.036 | 8.80 | 4.08 | ~ 
14 | 2.410 | 6.99 | 3.24 29°} 3.072 | 8.90 | 4.13 
15 | 2.467 | 7.15 | 3.32 30 Aid. LOT: Ge 4.18 
ee ee 
The first column contains the 30 numbers. ‘The second, the cube 
roots of them. The third, their products multiplied by 2.9, for 
tenths of inches; and the fourth, their products multiplied by 1.345, 
for hundredths. 
To measure the fall of rain in such a hollow cone, fixed with its 
base uppermost and horizontal, put down to its apex a stick of wood 
sharpened at its lower end, and mark the water-line on it; then the 
distance from that to the point of the stick, applied to a scale thus 
graduated, will show at once, in inches and decimals, the quantity of 
rain fallen; or the distance may be applied to a common scale of in- 
ches and decimals, and by comparing the length thus found, with the 
numbers in the third and fourth columns of the table, the same re- 
sult will be shown. 
