cclxxviii GENERAL SUMMARY OF SCIENTIFIC AND 



A number of mechanical novelties are worthy of mention. 

 Of these, perhaps the most interesting is the application of 

 the sand-blast for producing upon plated-ware or silver a 

 lustreless, very finely grained surface (called by the trade 

 a satin finish). The usual method of effecting this is by a 

 number of swiftly revolving brushes, made of fine wire. 

 The adaptation of the sand-blast for this purpose is said to 

 be perfect. The operation is exceedingly rapid, as the ar- 

 ticle has only to be turned so that the blast strikes for an in- 

 stant upon the required portions, the article being covered 

 by a rubber screen of suitable pattern. A self-feeding nail 

 machine, making sixpenny nails at the rate of 300 to 360 

 per minute, has lately been put in operation at the nail fac- 

 tory of the Albany Iron-works. Mr. M. Orum, of Philadel- 

 phia, has invented a very simple and perfect method of bend- 

 ing metal pipes, which consists in the employment of a close- 

 ly coiled spiral of square steel wire, of a diameter suited to 

 that of the pipe to be bent. This spiral is inserted into the 

 pipe, and acts as a flexible mandrel. When the pressure is 

 brought to bear on the pipe, this flexible mandrel affords it 

 an equable though elastic support, and permits the bend to 

 be accomplished in the most perfect manner, and in a frac- 

 tion of the time required by the method commonly used. 

 The so-called " Brayton Motor," which attracted consider- 

 able attention during the year, is an ingeniously contrived 

 engine, operated by the expansive force produced by the 

 combustion of a mixture of petroleum vapor (or gas) and 

 air. It differs in several essential features from other gas 

 and vapor engines. To avoid the inconvenience and loss of 

 time involved in fixing upon a lathe chuck, in the ordinary 

 way, certain special kinds of work, such as thin steel disks 

 or small circular saws, the ingenious artifice of converting 

 the chuck into a temporary magnet has been resorted to 

 with great success. Under these circumstances, the steel 

 pieces when placed on the face of the chuck are held there 

 firmly by the magnetic attraction, and when finished can 

 readily be removed by breaking the galvanic circuit and de- 

 magnetizing the chuck. The same principle has been ap- 

 plied to machine tools for holding articles of large diameter 

 and weight. The National Tube Works Company, in addi- 

 tion to making wrought-iron pipe of unusually large size, 



