OILING METHODS 55 



from 12° to 1 8° Beaume, while "stove distillate" 

 varies from 28° to 3 2°, and water-white kerosene from 

 40 to 42 . Knowing the specific gravity of the oil 

 purchased, it can easily be calculated how to mix with 

 lighter or heavier oil in order to obtain the required 

 consistency. Thus if kerosene (42 ) is at hand and 

 crude oil (15°), use about ten gallons of the former to 

 twelve gallons of the latter. For spring and autumn 

 use 28°-30° Beaume is to be recommended, while for 

 summer use a heavier oil at about 26 is preferable. 



How Applied. — Simply pouring on the oil with a 

 dipper is wasteful and requires some little time if all 

 the smaller adjacent pools of water to a given central 

 area are to be treated. Experience has taught that 

 the small, apparently insignificant, pools of water are 

 in reality the greatest menace and are commonly 

 overlooked. The use of a knapsack spray pump 

 (Figs. 21 and 26) of five-gallon capacity is highly 

 recommended. This can be strapped on the back 

 and will provide enough oil for three or four hours of 

 ordinary oiling on foot. Where it is out of the ques- 

 tion to use a horse and cart to carry the oil, the field 

 man can save himself many steps and some embarrass- 

 ment if he will make it a habit to carry a small quantity 

 of oil with him at all times in a pint or quart tin to 

 which is attached a rubber bulb and a spray spout. 



The inspector usually devotes a day or two to in- 

 spection and follows this with an entire day of oiling 

 and he may then need to use a good many gallons of 



