AGRTCULTURAI, MACHINERY AND IMPLEMENTS I 657 



parts to one part and from this part a single condxictor is led to earth. This 

 is a repetion of the 1914 experiment but considerabh^ more points were con- 

 nected to earth. 



The second method used a suction fan in order to prevent the formation 

 of an explosive mixture. 



These two methods have been used with success on some machines 

 whilst others which were not so fitted were burnt. 



Automatic fire extinguisher. — As it was not possible to demonstrate 

 that the above methods actualh' prevent explosions, the investigators de- 

 cided to reh' upon an automatic lire extinguisher which would afford pro- 

 tection irrespective of the cause of the fire. Such a device, illustrated in 

 the figure given here, is composed of the following parts : a tank A moimted 

 on top of the machine, contains a bottle C filled with sulphuric acid : a 

 discharge pipe H ; a tripping mechanism composed of operating levers G 

 and a main tripping le\-er L, : a trigger N ; discharge nozzles I ; and fuses F 

 mounted in a wire line. 



The tank is filled with a solution of carbonate of soda. In the discharge 

 line between the tank and the machine ma}' be mounted a three-way 

 valve from which a hose connection may be made for extinguishing 

 outside fires. 



The apparatus works as follows: the presence of sufficient heat will 

 melt one of the fuses F, break the line wire thus releasing the trigger 

 which frees the tripping mechanism. This breaks the bottle containing 

 the sulphuric acid which falls into the soda solution and sets free car- 

 bonic acid. This generates sufficient pressure to force the water through 

 the discharge pipe and the nozzles to all the cre\'ices of the separator. 

 The position of the fuses will vary with each machine and must be 

 selected so that they are sure to be reached b}- the flame or heat, but not so 

 placed that the wire connecting them is likely to be broken by the straw 

 or by the moving parts of the thresher. 



A full size working model was constructed and tested in the explosion 

 galleries of the Bureau of Mines at Pittsburgh, and 27 trials were made. 

 In no case did the extinguisher fail to operate successfullj'. Four different 

 types of threshing machines were tried at the Arlington Experimental Farm 

 and in each case the fire was extinguished before any damage was done. 



1209 - Mechanism for Clutching and Declutching the Feed Device in Straw Balers. — 



Deutsche Laihl'a'iiischnf'lichc Prcsse, 43nl year, Xo. 7.S p. 634, 2 li.ijures. Ik'rlin, vScplcinbcv 



27, igio. 



In automatic straw-balers different mechanisms have to be put in or 

 out of action from time to time, at fixed intervals, through the agency of 

 parts driven with a regular rotary or reciprocating mo\ement. The o])e- 

 rations are usually effected by means of a toothed wheel fixed in the compres- 

 sion channel which after a certain number of turns, brings about the neces- 

 sary' clutching. Now, as this toothed wheel moves slowly, it cannot give 

 a sudden movement; besides this requires a certain amount of power which 

 the toothed wheel can onl}^ give partly or not at all. 



These objections have induced Weloer Bros., of Seehausen (district 



