498 



♦ KNOWLEDGE ♦ 



[June 12, 1885. 



functions are opposed, then how shall we effect a compro- 

 mise t If, on the other hand, they go together in any 

 special material the desirability of using this material is 

 doubly indicated. 



These questions are answered by some very simple ex- 

 periments made by Rumford and described in a paper read 

 before the Royal Society ou March 22, 1787, and re- 

 published among his collected essays in 1802. I will 

 describe them in my next. 



{To be continued.) 



WATCH-MAKING AT THE INVENTIONS 

 EXHIBITION. 



( Contimied from p. 481 .) 



IN the press-room are made and stored all the hands, 

 wheels, balances, &c., that are made by stamping, or 

 punching, but in the screw department, Fig. 3, automatic 

 machinery is to be seen of the most ingeniou.s, and, at the 

 same time, most mathematically correct character. The 



little is the attention required that one boy is deputed to 

 keep seven of the-je screw-making lathes going. Of the 

 screws being made at the Exhibition it takes 250,000 to 

 make up a pound in weight, the value of the wire being 

 ten shillings. These screws, when finished, are valued at 

 XS.'iO, or seven hundred times the cost of the material, 

 which is, of course, of the best quality obtainable. In this 

 department there is also an automatic pin-making machine, 

 making 20,000 pins a day, for use in fastening hair springs. 

 The general roughing down of pinions, centre staff, and 

 other work of a kindred nature is also performed in the 

 screw department. 



The Jewel-making Department (Fig. 4) is unique and full 

 of interest. The stones used are generally rubies, sapphires, 

 and garnet-", the latter being derived from Bohemia and 

 Germany. Men are employed in superintending the jewel- 

 setting operations. The jewels, when broken into fit 

 fragments from the thin slabs or plates into which they are 

 sawn, are given to girls, who set each on a mandrel, round 

 it, centre it, drill it, and polish it, as is usual. They are 

 then parsed on to the assorters, who are also girls, and who, 

 with a gauge of the simplest construction, but capable of 



exhibit includes one of these screw-cutting machines. Here 

 will be seen a piece of steel wire 20 inches in length, 

 automatically feeding into the machine. A small section 

 of the wire is turned down, a die then approaches it and 

 cuts a thread, and shapes a point on the reduced portion. 

 A cutter divides this screw, together with a sufficient length 

 of unreduced wire to form the head, from the main length. 

 A carrier comes over, clutches the screw, takes it away, 

 and places it in position for a revolving cutter to make the 

 slot intended for the screwdriver, another tool then coming 

 up and removing the burr from the screw-head. The 

 screw being complete, a little rod is urged forward 

 against it, driving it out of the carrier into a receptacle 

 for the finished screws. This machine is capable of 

 turning out 4,000 screws per day, the total output 

 at the factory being 100,000 i)er day. All the atten- 

 tion that is required is to insert a length of wire 

 in the machine as the previous length is used up. Even 

 the lubrication is automatic (as it is with all the other 

 machines), a fine stream of oil being directed on to the 

 material as it is being worked from a reservoir, to which 

 the oil again finds its way after leaving the machine. So 



indicating instantly, and for the most rapid inspection, 

 the 1-100, 000th of an inch, assort them according to 

 their apertures. The jewel-setter then takes them, 

 and placing one on a plate at the top of the 

 rest of the lathe, which holds the tiny plate des- 

 tined to receive the jewel, brings up a gauge against the 

 jewel, pressing it lightly against a rib placed for that pur- 

 pose, and by so doing sets the cutter, so that the hole 

 which it cuts shall be exactly gauged by the jewel itself, 

 and the jewel is fitted with absolute precision, and it is 

 then in a moment burnished into its plate, which is then 

 ready to be fastened into its place in the works by two of 

 the tiny screws spoken of. The jewel gauge consists of a 

 tapering needle, on which the jewel is threaded and which 

 is then pashed back into a perforated holder until the 

 jewel touches a collar placed for that purpose. At the 

 inner end of the needle is an index, which shows on a scale 

 the distance which the needle has been pushed into the 

 collar, and thus shows the diameter of the needle at the 

 point where the jewel stopped. Nothing can be simpler or 

 more easily legible, and it will indicate to the naked eye 

 even differences in the aperture of l-2.500th of an inch. 



