August 3, 1888. | 



SCIENCE. 



1-27 



Total wheel base 1:5 ft. 4 in. 



Weight in working order .... 31,000 lbs. 



Weight on <lrivers 26,000 lbs. 



Water-capacity of tank 500 gallons. 



Messrs. Porter state that a similar engine, 

 working day and night on a road 11 miles in 

 length, with grades of .t'i feet per mile, lias 

 handled 3.50. OOO feet of logs in i\ hours, run- 

 ning about ISO miles in that time. 



The engine exhibited is well designed, and 

 the workmansliip is fully equal to that on a 

 first-class main-line engine. 



The Cooke locomotive works of Paterson. 

 N.J., exhibit an engine for the Southern 

 Pacific railroad which is believed to be the 

 largest locomotive in the world, the cylinders 

 being 20 inches diameter by no less than .'iO 

 inches stroke. The designer of this engine, 

 Mr. N. I. Stevens, general master mechanic 

 of the Central Pacific railroad, is, however, 

 building a still larger engine at tiie company's 

 shops at Sacramento, Cal., the cylinders of 

 which measure 21 inches by 36 inches. This 

 latest development will exert a tractive force 

 of 278 pounds for every pound per square inch 

 average pressure on the pistons ; that is to say. 

 with an average pressure on the pistons of 100 

 pounds per square inch throughout the stroke, 

 this engine would exert a tractive force or 

 pull of 27,800 pounds, less the internal friction 

 of the working-parts of the engine. Whether 

 the average drawbar of the average freight- 

 car is capable of safely standing such a strain 

 is a question which experience will probably 

 solve in a direction unfavorable to weak draw- 

 gear. Apart from their immense size, these 

 engines are interesting as being fitted with a 

 novel form of valve-motion. The engine ex- 

 hibited lias four slide-valves to each cjlinder. 

 two main valves, and two riding cut-oflT valves. 

 An excellent diagram is obtained, the cut-oft' 

 being sharp, and the compression very slight ; 

 and the gear seems well adapted to a slow-run- 

 ning freight-engine. In the later and lai'ger 

 engine, but two valves are employed, and but 

 one eccentric ; motion being taken from the 

 engine crossbead. The results of this simpler 

 gear promise to be equally good, and the trial- 

 trip of this engine will be looked forward to 

 with great interest. 



The Grant locomotive works are the makers 

 of the only engine whicli departs from the 

 sober suit of l)lack in which its competitors are 

 arrayed ; and further examination shows tliat 

 its pecidiarities are not confined to the outside 

 appearance, but extend to the fuel to be used, 

 whicli is entirely novel in character. The in- 



ventor, Dr. Holland, proposes to raise steam 

 by means of the combustion of decomposed 

 water. The heat evolved by burning naphtha 

 is used to separate the oxygen and hydrogen 

 in superheated steam ; and, the carbon of the 

 naphtha kindly uniting with the oxygen thus 

 set free, the hydrogen is burnt bj' means of 

 oxygen 'obtained from atmospheric air. The 

 inventor states that the only products of this 

 combustion are carbonic acid and water, the 

 nitrogen disappearing in some mysterious man- 

 ner not yet fully understood. The old fallacy 

 tliat water can be decomposed and then re- 

 united, with a positive advantage as regards 

 heat, is here again illustrated ; while the strong 

 smell of burning naphtha during the trial of the 

 engine in the exposition indicated that this 

 convenient auxiliary was used to a considerable 

 and probably wasteful extent. 



The Philadelphia and Reading railroad ex- 

 hibit a fast passenger-engine fitted with Woot- 

 tens' patent firebox, which is adapted to burn 

 any waste or inferior quality of fuel. He- 

 versing the usual practice on locomotives, the 

 combustion on this engine is slow, owing to the 

 enormous area of the grate (72 square feet), 

 instead of a small one (10 or 17 square feet), 

 while the blast is not severe, and the fire is one- 

 tliird the usual thickness (1 inches instead of 

 10 or 12 inches) ; the result being a less vivid 

 combustion, the interior of the fire-box being 

 dull red in place of the white heat usual when 



