MECHANICS AND USEFUL ARTS. 39 



& Co., Great Queen Street, Westminster, these plates being 

 bolted to the wheel-tire and further secured by iron rings. The 

 front pair of driving-wheels of the engine are 3 feet 6 inches in 

 diameter, and are fitted with India-rubber segments 12 inches 

 long, 4 inches wide, and 3 inches thick. The rear pair of driving- 

 wheels are 5 feet in diameter, and are fitted with India-rubber 

 segments 12 inches long, G inches wide, and 3 inches thick. The 

 rubber is firmly attached to one-fourth inch steel plates, which 

 are bolted on to the one-half inch wrought-iron tires, the seg- 

 ments being still further secured by five-eighths inch wrought- 

 iron rings placed on each side of the wheel. 



The trial, which was conducted by Messrs. Aveling & Porter, 

 took place on Friday last in the presence of a number of govern- 

 ment officials, and some of our leading engineers. The engine 

 started from Messrs. Aveling's works, at Rochester, with 2 

 long 4 wheel lorries and a load of iron girders, giving a total 

 weight of about 13 tons. It proceeded at a pace of about 4 miles 

 an hour through the slippery streets of Rochester, travelling 

 steadily up Star Hill, which has a gradient of 1 in 12 for more than 

 300 yards. It made several sharp turnings round corners, the 

 radius of the path of travel being not more than 15 feet. With 

 one ordinary iron skid on the rear wheel of the hindmost lorrie, it 

 descended Rome lane, a steep falling grade, under complete 

 control. The rough and irregular stone causeway, the timber 

 bridge way of the Chatham dockyard, and the rough and broken 

 ground near the landing quay on the Medway, were all smoothly 

 and successfully traversed. The girders were landed on the quay 

 and the engine then returned to Rochester. The ground near 

 the landing quay is full of hillocks of cinder, clinker, stone, 

 bricks, scrap iron, etc., but, although the engine ran over all 

 these substances, not a cut nor permanent indent was to be found 

 afterwards in the India-rubber segments. 



The great advantage of Messrs. Sterne's method of attaching 

 the India-rubber in segments over the solid ring is, that if a seg- 

 ment gets damaged it is easily and quickly removed and re- 

 placed by a spare segment at a moderate cost. The motion of 

 the engine during the run was easy, and the India-rubber readily 

 impressed itself into the inequalities of the roadways. To avoid 

 all possibility of slip in wet streets and on clay soils, Mr. Aveling 

 proposes to introduce steel staples or crossbars, so arranged as to 

 take the traction without neutralizing the benefit derived from 

 the elastic action of the rubber. There is no doubt a decided ad- 

 vantage in Messrs. Sterne's method of utilizing the India-rubber. 

 Traction engines with their wheels thus tired will prove useful 

 under the special local circumstances, such, for instance, as 

 where they have to traverse paved or very uneven roads. But 

 here, to our mind, the advantage of rubber-tired wheels ceases, 

 and we believe that the engine in question, or, in fact, any of 

 Messrs. Aveling & Porter's engines, would work as well without 

 as with this addition, and that in most cases the 130Z. or 140Z. 

 which these appliances cost could be more profitably expended 

 on the engine in other ways. 



