1920] 



RURAL ENGINEERING. 87 



The results of technical investigations are given together with graphs of data 

 and drawings of apparatus perfected. 



It is concluded that gas traction is fully as safe as any other system of 

 mechanical traction, even when the gas is contained in exposed flexible con- 

 tainers, and that in its newer forms of application merits adoption as a 

 lonmiercial alternative to electric, petrol, and steam traction. The average 

 traction equivalent of 1 gal. of petrol was found to be 250 cu. ft. of ordinary 

 town gas. 



" Semirigid containers made of rubber and canvas are unsatsifactory, but 

 semirigid containers made of an inner rubber bag suitably restrained by an 

 outer member of woven steel wire with metal end plates, and complying 

 with . . . approved specification, appear to be satisfactory for internal pres- 

 sures not exceeding 45 atmospheres, although results of endurance tests in 

 service are not yet available. The time has come to approve and encourage 

 the use of metal cylinders made of high-carbon or certain alloy steels to con- 

 tain combustible gases at high pressures for traction purposes, and such metals 

 can now be safely so employed for working pressure up to 2,2.50 lbs. on the 

 square inch. Subject to the adoption of simple precautions specified, there is na 

 risk of explosion with town gas during its compression into cylinders or its use 

 from them. Wire-wound metal cylinders with removable ends held in place by 

 screwed tension rods lose gas at the joints after the earlier stages of discharge, 

 and are heavier for any given volume of gas than plain cylinders made of 

 liigh-carbon or alloy steels." 



The total cost of compressing gas into cylinders was found to vary between 

 30 and 70 cts. per 1,000 cu. ft. of free gas. The average power yields obtainable 

 from an ordinary motor vehicle engine unaltered structurally as regards com- 

 pression space are accepted as follows : Town gas of 450 B. t. u. per cubic foot, 

 91 per cent of petrol, suction producer gas of 210 B. t. u. per cubic foot, 87 

 per cent of petrol, and suction producer gas of 140 B. t. u. per cubic foot, 82 

 per cent of petrol. 



" The risk of escape of unburnt carbon-monoxid gas from a suction-gas plant 

 In a motor vehicle is not such as to call for the exercise of special precautions 

 exceiit while the vehicle is at rest overnight witliin an inclosed structure with 

 the fire still burning in the producer. The water-feed to a portable suction-gas 

 producer can be so adjusted as to increase the calorific value of the issuing 

 gases by as much as 50 per cent on a consumption of water falling as low as 

 25 per cent by weight of the simultaneous consumption of anthracite or coke. 



" Suction gas, employed alone or partly hydrogenated with water-gas, should 

 in the near future prove a suitable alternative fuel for use in any internal- 

 combustion engine primarily designed to run on alcohol. Physical difficulties 

 of storage and conveyance in conjunction with allied considerations of cost 

 render the use of liquefied hydrogen, methane, carbon monoxid, or ethylene, 

 which gases are or may shortly become available for liquefaction on the large 

 scale, confraercially impracticable for traction work. There is an increase of 

 weight when an absorbent material is introduced, compared with that when 

 cylinders containing only gas iinder compression are used, for any given 

 volume of free gas, and no saving in the total cubic space occupied. The 

 necessary extra provision to utilize systems for enriching gas in any vehicle 

 does not yield commensurate advantage, with possible but as yet unjiroved 

 reservations in favor of the use of acetylene or naphthalene." 



Fundamentals of tractor design, G. T. Strite (Trans. Soc. Automotire 

 Enfiin., 13 (1918), pt. 1, pp. 196-204, fig. 1).—A discussion of tractor design, with 

 182230°— 20 7 



