TRANSACTIONS OF THE SECTIONS. 231 



tlie power when working without feed in an abnormal manner, viz. with both the 

 disks revolving in the same direction and at equal speeds. The experiments and 

 their results may be tabulated as follows : — 



Power required to drive a Carr's 7-feet Disintegrator imdev different conditions at 

 about 400 revolutions per minute. 



Gross indicatoed 

 horse-power. 



When converting into flour 20 quarters of wheat per hour .... 145 



"When converting into flour 15 quarters of wheat per hour .... 123 



AVheu worldng in the normal way, but without feed 63 



When worldng with the disks lashed together, so as to revolve 



in the same direction and at the same speed 19 



From this Table it will be seen that when the machine'is worldng abnormally, it 

 only requires 19 horse-power to drive it, this power being employed in overcoming 

 the friction of the journals &c., and in driving the disks while acting on the air, 

 after the manner of an ordinary fan. Directly, however, the machine is piit to 

 work in its normal way, so as to deal with the air by repeated reversals, the power 

 mounts up to G3-horse. It will also be seen that to make 1-j quarters of wheat 

 into flom' reqiures 60 horse-power more than to work the machine when acting 

 upon air alone, or at the rate of 20 horse-power for each 5 quarters of wheat, a rate 

 that is very fairly corroborated by the increased power of 22 horses, as shown by 

 the Table to be necessary when the feed is increased b}' 5 quarters, viz. from 15 to 

 20 quarters per hour. 



Further experiments were made with the object of ascertaining the power ab- 

 sorbed whilst rimning the machine empty at varying speeds. As this, however, 

 could only be done by altering the revolutions of the steam-engine itself, there were 

 practical difficulties attending the experiments which rendered any great range 

 impossible, and also somewhat impaired the accuracy of those which could be 

 made. 



The general I'esult, however, showed that the power, as was expected, varied as 

 the cubes of the speeds. 



Although it appeared, from the foregoing experiments, that the Carr's machine 

 when running empty takes, in round numbers, 50 per cent, of the power used by it 

 when at work upon 15 quarters of wheat per hour, it must not be supposed that it 

 is an uneconomic machine as compared with mill-stones. On the contrary, both in 

 power consumed and space occupied, the comparison is gi'eatly in its favour. To 

 grind 20 quarters of wheat per hour would require at least 20 pairs of 4 feet 6 

 millstones at work, and these would demand from 200 to 250 horse-power, and 

 would occupy, including the necessary spare stones for dressing, about fifteen times 

 as much space as the disintegi-ator. 



On this point of " dressing," Carr's machine possesses a further gxeat advantage. 

 With ordinary millstones one sixth of the number are always out of work for this 

 purpose ; and not only are they thus idle, but the wages of highly skilled stone- 

 dressers have to be paid. In the Disintegrator nothing analogous to " dressing " is 

 required. The wearing parts are the studs ; and j udging fi'om appearances, it 

 would be many years before they require renewal. The machine from the principle 

 of its action possessing this peculiarity, that a worn stud, so long as it is strong 

 enough to beat the particles without sensibly yielding to them, will do its work 

 just as well as when it was new. 



It woiild be beyond the scope of this paper to enter into the question of the 

 relative qualities of the products of this machine and of ordinary millstones. It 

 ought, however, to be stated that Mr. Gibson expressed himself to the writer as 

 highly satisfied on this point. 



On a direct-aciinrf Comhined Steam and HydrauUc Crane. 

 By A. B. BEOwif. 



