760 REPORT— 1891. 



hination of these two methods, by means of which a sprayed jet of oil is first broken 

 up by compressed air playing on it in the inverted spray-nozzle, then it is further 

 mixed with air, heated and completely vaporised by the hot products of combustion 

 from exhaust led round this vaporiser or mixing chamber, before being allowed to 

 escape. This might be called a reye?ie?-«<o?-. The oil vapour thus thoroughly mixed witli 

 air in the proper proportions is drawn through an automatic suction valve into the 

 engine cylinder by the piston in its forward stroke. The action of this spray-maker 

 (shown) will be seen by the following experiment: — First, turn off the air supply and 

 a flame does not light the unbroken oil-jet ; next, allow the air under pressure to 

 break up and thoroughly spray the oil, the vapour formed is so intimately mixed 

 with air that it can easily be ignited, and burns with a bright flame. (The draw- 

 ings of this spray-maker showed the governing arrangement adopted in the 

 Priestman engine.) The amount of hydro-carbon is diminished or increased, together 

 with the amount of air, so as to form a high explosive charge or a low one, accord- 

 ing to the amount of work to be done by the engine. The air through the wing- 

 valve is rightly proportioned to mix with the oil which is allowed through the 

 V-shaped slot cut in the conical plug regulated by the governor. By this means 

 there is a regular explosion and impulse, every cycle giving admirable regularity of 

 running. (Indicator-cards illustrating this mode of governing with full load and 

 running light were shown.) The compressed charge is Jived by an intermittent 

 electric spark, made to play between ends of two platinum wires insulated by 

 porcelain in the igniting plug (shown), and connected to an induction coil excited 

 bv a storage-cell of about two volts, which has been known to work for more than 

 l",100 hours. 



The author explained the action in horizontal engines by means of diagrams, 

 and gave a short description of a double cylinder vertical launch engines specially 

 designed for running at a high speed with the centre of gravity kept low. Each 

 cylinder of launch engine is 7 inches diameter by 7 inches stroke, arranged to give 

 an explosion or working stroke every revolution of fly-wheel. The actual horse- 

 power at 250 revolutions per minute is 57, and 91 indicated horse-power. These 

 engines are working in a small launch 28 feet from stem to stern by 6 feet 2 

 inches beam, and are giving good results. Speed 7 miles, and engines work 

 with regularity. These engines are now in use on barges in canals, and also for 

 deep-sea trawling. The horizontal type is remarkably self-contained, and well 

 adapted for isolated electric lighting installations and lighthouse work. It is 

 used for pumping and hauling in collieries, and for rock-drilling in mines; in 

 fact, its sphere of usefulness is rapidly extending, because it is found reliable and 

 steady at work, with decided economy of fuel. 



The main object desired in oil-engines is to prevent clogging in the cylinder, 

 so that the engine may run without attention or frequent cleaning. This is secured 

 by thoroughly mixing the air and vapour, so as always to form an explosive 

 mixture which gives complete combustion and clean exhaust. It must be pointed 

 out, however, that during the compression of the charge before ignition a con- 

 siderable proportion of the vapour comes into contact with the walls of the 

 cylinder, condenses on them, and never gets burned, however useful it may be for 

 lubrication. This the author has proved by comparing the pressure along the 

 compression curves of the indicator diagrams, wilh the pressure obtained by 

 experiment from each charge consisting of the explosive mixture -015 cubic inch of 

 oil and 191 cubic inches of air at the same temperature. Taking the tempera- 

 ture of the charge 170° F. on entering the cylinder, the indicator diagram shows 

 the highest pressure before ignition only 38 lbs. per square inch. This pressure 

 is kept low for fear of much condensation, as well as to give smooth running. 

 In the gas-engine we know that compression of the charge before ignition is essen- 

 tial to high efficiency, and similar considerations lead one to expect the same to 

 hold true for oil-engines. Indeed, by adding fresh air to the charge after leaving 

 the vaporiser, and compressing more than usual, greater power or higher efficiency 

 is obtained, but the temperature of the cylinder liiecomes too high for lubrication. 

 In some published trials an engine may be run with a special cylinder liner to 

 withstand the high temperatures due to high compression used, but these are not 



