1874.] Fuel Economy. 201 
temperature of blast-furnaces, gas retorts, and other useful 
purposes where high temperatures are used. 
Bailey’s Oil Tester is a very ingenious instrument for 
finding out the value of oils as lubricants; and if good oil 
is used for lubricating, it reduces friction in the machinery, 
and thus saves coal and wear'and tear. The tester may be 
briefly described as a piece of 3-inch shaft and two brass 
steps, upon which frictional pressure is obtained by weighted 
levers ; a thermometer is fixed upon the machine, to denote 
the temperature. One drop of oil is put on to a drum of 
3 inches diameter, friction is applied, and the ‘“‘ life-time ” of 
the oil (which is the technical term) is indicated by means 
of a speed indicator, which indicates the number of revolu- 
tions required to raise the temperature a given number of 
degrees. The exact. money value of oil may be arrived at as 
follows :—Suppose a certain quantity of No.1 oil on the 
machine shows 200° by being driven 10,000 revolutions, 
No. 2 oil shows 200° and 7500 revolutions, or 25 per cent 
less value. In addition to this practical way of obtaining a 
result, the machine may be driven to a higher temperature, 
to see which oil produces the worst residue. In testing 
various oils, a certain weight or measure must be taken; 
the thermometer should always indicate the same tempera- 
ture at starting. It is found that 200° F. is the best to try 
all oils to, if their lubricating power is to be consumed, and 
the machine should be always driven until that temperature 
is indicated, and then immediately stopped ; the bearings of 
the spindle should be well oiled, to prevent friction in the 
wrong place; when a temperature.of 200° has been obtained 
(the speed index showing zero at the start), it should then 
be seen the number of revolutions taken to produce the 
temperature. After testing the oil, it is directed that the 
machine be stopped, and the oil is to remain on the machine, 
and in twelve hours after it is to be tested again to see how 
soon 200 can be obtained; the second experiment will 
indicate which oil is the inferior on machinery when stopped. 
The following is a short table of results on trying these 
various kinds of oil :— 
: Total Market Real value of 
Quality of Temperature indicated Price the Oils, 
Oil produced. Speed of per taking No. 1 
Three Tests. gallon. asa standard. 
s.d. Saas 
Ide Tots! « 200 120,000 Ong 60 
Rite esp ica) 3, (200 180,000 40 g 0 
NS ser, oo 200 60,000 2 6 30 
It will be seen that No. 2 oil will allow 50 per cent more 
