242 



CANADIAN FARM YEAR BOOK. 



(the pint used here is U.S. measure, 

 and is smaller than our Imperial 

 pint). 



Horse Power. 



The horse-power of a gasoline en- 

 gine is obtained by the same for- 

 mula as is used to determine the 

 horse-power of a steam engine, 

 namely, horse-power equals P x L x. 

 A X N, divided by 33,000, where P 

 equals the mean effective pressure 

 In lbs. per square inch, L equals 

 length of stroke of the piston in feet, 

 A equals area of piston in square 

 inches, and N equals number of 

 power strokes per minute. It must 

 be remembered that the number of 

 power strokes, N, is only one-fourth 

 of the total number of strokes per 

 minute. 



The pressure in the cylinder varies 

 greatly during the power strokes. 

 When the explosion occurs it is very 

 high, usually about 400 lbs. per 

 square inch. It drops rapidly as the 

 piston moves. The mean effective 

 pressure is determined from indi- 

 cator cards, and the horse-powei 

 calculated from this is called the in- 

 dicated horse-power. It is a difficult 

 matter to determine this mean effec- 

 tive pressure, and for this reason the 

 horse-power is usually found by ex- 

 periment by means of a prony brake 

 on the fly-wheel. This gives the 

 brake horse-power. 



SCORE CART> FOR GASOLINE 



ENGINES. 



Total Points 100. 



Design and Economy of Operation 54 



Points. 



Simple contrivance for opera- 

 tion of valves 5 ptp. 



Working parts and gasketted 



joints easily accessible 7 



Rated horse power equalling 



brake H.P 14 " 



Oiling system complete and 



easily accessible 9 



Ample cooling surface 3 " 



Ample space for safe storage 



of gasoline 2 



Ample valve area 2 



Standard type of Governor. . 2 

 Standard type of Ignition 



Qttq+pjYI •• " 



Standard type of Carburetor. B " 



Workmanship and Material 84 

 Points. 



Close but easy fit of all parts 9 pts. 



General finish and appearance 6 " 



Bearings of brass, babbitt or 

 well known composition 

 made easily removable ... 9 " 



Parts bearing strain of ample 

 size and made of steel 



when necessary 10 " 



Operation 12 points. 



Ease of starting 5 pts. 



Steadiness in running 4 " 



Noiseless operation of valves 3 " 



Total 100 pts. 



Note. — This score card is intended 

 for the use of the buyer of a gasoline 

 engine. In comparing engines he 

 may take the statements of the 

 manufacturer and use the score card 

 to prevent too much importance be- 

 ing laid on a minor point. 



A certain amount of technical mat- 

 ter necessarily enters into this score 

 card but questions on any points ad- 

 dressed to Canadian Farm will be 

 answered through its columns. 



Gilson "Goes Like Sixty'' Engine 

 The Engine of Quality 



For all power purposes. Canadian 

 product of highest class. Scientifically 

 and mechanically correct — combining 

 service, convenience, reliability and 

 efficiency to an unequalled degree. 

 Equipped with easy starting, speed 

 changing, and spark retarding device. 

 High tension, oscillating magneto, no 

 batteries. Sold subject to trial and 

 approval. Write for bulletins on en- 

 gines, farm implements, pumps, etc. 



GILSON MFG. CO., Limited, 

 86 York St., Guelph, Ont. 



