154 
1. Heat evolved per hourby the wire 110 -66 x (gj = 27 - 665 units. 
2. Consumption of zinc per hour 535 25 x i = 267 ‘62 grains. 
u 
3. Heat due to 267 '62 grains 1 1 0*66 x i = 65-33. 
4. Therefore the work per hour will be (55-33-27-665)772 
= 21357. 
21357 
5. And the work per grain of zinc will be 267-62 = ^'8 or I °f 
the maximum duty. 
IV. If the load be still further reduced and velocity in- 
creased so as to bring down the current to \ of what it was 
when the engine was still, or to '4653, shown by a deflec- 
tion of the galvanometer of 24° 57 ' we shall have 
1 . 
2 . 
3 . 
4. 
5. 
Heat evolved per hour by the wire 110 - 66 x = 12-294 units. 
Consumption of zinc per hour 535-25 x; = 178-42 grains. 
o 
Heat due to 178-42 grains 110-66 x i = 36-89 units. 
Therefore the work per hour will be (36 - 89 - 12-294)772 
= 18988 ft. lbs. 
18988 
And the work per grain of zinc will be - 106-4, or § of 
the maximum duty. 
V. Remove the load still further until the velocity in- 
creases so much that the current is brought down to to<r of 
its quantity when the engine is still. Then we shall have 
1 . 
Heat evolved per hour by the wire 110-66 x 
( m ) ’= -011066 
of a unit. 
2. Consumption of zinc per hour 535-25 x -^ = 5-3525 grains. 
3. Heatdueto5-3525 grainsof zinc 110-66 x ^ = 1 "1066 units. 
4. Therefore the work per hour will be (1-1066 - -011066)772 
= 845-73 ft. lbs. 
845*73 
5. And the work per grain of zinc will bo 57352 =15® or 1 V 0 
of the maximum duty. 
When the velocity increases so that the current vanishes 
the duty = 159 6. 
