MECHANICS AND USEFUL ARTS. 121 



compensate for this influence. The present scale receives the grain in a large 

 stream until the proper weight is nearly attained, then by closing the principal 

 gate and receiving a small stream finishes the operation with all the nicety 

 desired. 



FILE-MAKIXG BY MACHINERY. 



For the last 20 years skilled mechanics have exerted all their ingenuity 

 in trying to discover a process of manufacturing files, so as to lessen the cost 

 of production. Some firms in Sheffield and elsewhere are said to have spent 

 fortunes in experimenting, in the hope of attaining this end, and have still 

 failed. A machine, which has proved successful, has recently been invented 

 by Mr. Ross, of Glasgow, Scotland. The merit of the invention will be best 

 understood by the general public, when it is stated that by its agency files can 

 be struck, and that in a superior manner, with an advantage hi labor alone 

 of at least 200 per cent over the old process of hand-striking. A skilled file- 

 cutter will strike by the hand somewhere about twenty common 40 inch flat 

 bastard files in a day. One of Mr. Ross's machines, under the direction of a boy, 

 will strike sixty files hi the same amount of time. The machine is so simple 

 too, that an uninitiated boy can hi a few hours be instructed to attend it. A 

 one-horse steam-power is capable of driving six of these machines, and with 

 some practice, a lad might be able to attend two of them, for they possess the 

 attribute of stopping of themselves when a certain portion of work has been 

 completed. A comparative glance at the hand-made and machine-struck file 

 at once shows the superiority of the latter, even were the other advantages 

 altogether kept out of view. Flat bastard or equaling files, common and 

 tapered, are those most in use, and are the kind which Mr. Ross's invention has 

 been mostly hitherto engaged in producing ; but the machine can be modified 

 to strike rounds and all the other variety of files. As was to be anticipated, 

 the machine-made files have already found their way extensively into use, 

 although only a few months have expired since the process of manufacture was 

 begun. North British Mail. 



CARPENTER'S ROTARY PUMP. 



A pump recently invented by Mr. S. D. Carpenter, of "Wisconsin, is worthy 

 of attention from the simplicity and at the same time singularity of its mo- 

 tions, the fewness of its parts, its small cost of construction, its economy of 

 space, and evident durability. The whole pump consists of a metallic case, in 

 which is inclosed a vertical shaft with a nearly hemispherical mass of metal 

 at its lower extremity, and a vibrating or oscillating feather. When impelled 

 by a continuous power, as in filling up tanks at rail-road stations, the shaft 

 may be safely driven with considerable velocity, and the pump may be con- 

 sidered tolerably perfect without the aid of any packing. It is questionable 

 whether the rotary motion is easier than the reciprocating for pumps worked 

 by hand, but where power is employed for the raising of considerable quanti- 

 ties, the invention of this pump renders it unnecessary and highly impolitic to 

 convert the rotary motion of the shaft into any kind of a reciprocating action. 



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