of the Vienna Exhibition, 1873. 



73 



burnt straw deposited themselves on the bars, forming a clinker which very 

 much impeded the ingress of atmospheric air, and in order to get over this 

 difficulty a simple arrangement of sHding blunt knives was devised, which cut 

 out the deposit when it became too thick. A jet of water was also arranged to 

 extinguish the burning ashes in the ash-pan before they could be blown about. 

 The apparatus for feeding the engine with straw, &c., is self-acting, and driven 

 from the boiler by means of a strap, but it can be easily disconnected, and the 

 ordinary fire-door substituted in its place, when it may be expedient to burn 

 wood or coal. When it is necessary to get up steam, straw may be employed 

 in the same way as any other combustible, by attaching a handle to the feed- 

 rollers and turning them by hand instead of steam power. The straw is 

 usually placed alongside the trough, and one man only is required to supply 

 the engine with fuel when it is at work. The average consumption of straw 

 is about four or five times the weight of coal, and, according to experiments 

 made both in England and Paissia, ten to twelve sheaves of straw are required 

 to thresh 100 sheaves of wheat. * * * * Picr_ 24 is a section of the 

 fire-box, and Fig. 25 an end view, of which the following is a description. 



Fig. 25. — End View of the Fire-box in Messrs. Head and ScJierniotlis 

 Straw-burning Portable Engine. 



* * * * * a, a are teethed rollers fitted with malleable teeth and con- 

 nected with the engine by means of a pulley h, driven by a strap from 

 the crank shaft. These rollers make 48 revolutions per minute, and can be 

 turned by hand when getting up steam, c, c are the movable sliding blunt 

 knives, or rake, attached to a cross-bar d, sliding on guides e, e below the 

 grate. This rake can be moved with a forward and side motion by the 

 stoker, by means of the handle /, and thus break up the silicious crust de- 

 posited on the grate bars g. h is a, perforated pipe for injecting water on the 

 burning ashes, i is a shoot for carrying any small pieces of ignited straw back 



