AMERICAN INSTITUTE. 5S5 



MR. fisher's paper. 



The first requisite of a system of transportation for cities is, that it be 

 free from dust and mud ; the second is, that it be practicable for all kinds 

 of vehicles to go wherever required ; the third is, that it be capable of 

 high speed with safety ; the fourth is, that the vehicles be ventilated and 

 warmed when desirable; the fifth is, that it be as cheap as is consistent 

 with the general style of living and rate of expenditure of the majority of 

 those who habitually use it. The foundation of a system of transportation 

 is the road. But the road must be suited to the power. If we are to have 

 horse power, the road must be so rough that the horse can have a secure 

 foothold ; if we are to use a power borne on wheels, we may make the road 

 smooth. I shall first consider the road, assuming that the power is to be 

 borne on wheels. Iron is admitted to be the best material, and the cheap- 

 est, where the traffic is sufiicient to keep the interest on the cost relatively 

 low. 



For the thoroughfares of this city I shall consider iron the material, 

 taking it for granted that no proof on this point will be required by the 

 persons whom I address. 



The power required for traction on iron rails, with railway wheels 

 moving very slowly, is 3 lbs. per ton for the rolling resistance, and about 

 the same for the friction of axles of 3 inches diameter ; and for the resist- 

 ance of cohesion there is one-eighth of a pound for each mile per hour, or 

 2 lbs. for 6 miles per hour. This is the conclusion from experiments by 

 Harding and Scott Russell. 



But the axles of light carriages do not average more than 1^ inches 

 diameter, hence 1| lbs. per ton would be their resistance ; and the wheels 

 of common carriages are one-half larger than railway wheels ; hence the 

 resistance would be reduced to 1 lb. per ton at the axles. Moreover, the 

 resistance of cohesion and rolling was found by Morin to be inversely, as 

 the diameter of the wheels ; but this is disputed by others, who hold that 

 it is inversely as the square root of the diameters. If Morin be right, 

 these resistances would be reduced from 5 to 3^ ; and if the others be 

 right, they would be reduced from 5 to 4.008 lbs. per ton ; and the total 

 resistance, at 6 miles per hour, would be 4^ lbs. in the one case, and 5 

 lbs. in the other. 



The last figure is an eighth of the resistance which Marriote fisund on 

 the Piccadilly pavement at 2^ miles per hour. 



The weight of an omnibus is fully equal that of its load, but if it run 

 on an iron floor its weight might be reduced, and hence less power could 

 work it. The English stages on Macadam roads used to weight from 16 to 

 18 cwt., and sometimes carried 40 cwt., and yet lasted a long time ; on an 

 iron floor they could have been still lighter. 



In Chatham Square, on the ascending line, there are iron horse tracks of 

 a bad form, and not firmly connected to the wheel tracks. It would be 

 better to cast the horse tracks in broad plates, as proposed by Mr. Jordan 

 Mott, and to bolt the rails to them. Still better would it be to make the 



