44 ANNUAL OP SCir.NTinC DISCOVERY. 



registorin<x apparatus takes account of both the strain and the 

 speed, while tlie simple index lirst described measures only the 

 strain. 



This instrument is at once eleji^ant in desio^n, simple and there- 

 fore eheaj) in its construction, easily verilieil and proved at any 

 moment when in operation, and of very easy application to any 

 machine, or set of machines, driven by hired poAver, whether the 

 power used be constant or varial)le in amount. The instrument 

 admits of a great variety of forms ; the one described above is 

 meant for the end of a shaft ; anotlier form is so arranged as to 

 be attached at any part of a running shaft, while in the propor- 

 tions and dimiMisions of the several parts there would be the same 

 variety as in conunon scales, which are large or small, coarse or 

 fine, according as they are meant to wa^igh coal or pills, hay or 

 coin. The instrument meets a pressing want. Tea and sugar 

 are sold by the pound, gas by the thousand feet, cloth by the yard, 

 but steam-i)ower and steam and air engines are sold by guess- 

 work, or liy rougli and uncertain rules, on whose api>lication 

 buyer and seller can seldom agree. 



ileri'after steam-power can be sold by the thousand or million 

 fo()t-])ounds. 



Mr. lluggles does not jiatent his valuable invention. 



RUGGLES'S SHAFT-COUPLING. 



There are some mechanical powers, which, because of not being 

 of universal or general applii'ation, are seldom uschI and recog- 

 niztMl, but which are of a most im])ortant and valual)le character. 

 Such is the dilVerential screw, which is rarely used, but which, in 

 certain instances, is the strongest grip known in mechanics. Tliis 

 has been a])])lied in the above improvement very effectively. 



It is a dillerential screw-ljolt having two threads, that on the 

 upper poi-tion being ten to the inch, and that on the lower part 

 nine to the inch. The head of the bolt is six-sided, and is flush 

 with the surface of the box. It is seated in a circular recess, 

 which is large enough to receive on the end a cylindrical or 

 socket-wrench. Threads corresponding with those on the two 

 portions of the bolt are taliped in the boxes made to fit the shaft. 



The above is sufficient to explain to any practical man the 

 operation of this device. It Avill readily be seen that a few turns 

 of the screw will be sufficient to clamp the shaft-ends in a grip, 

 the power of which is limited only by the strength of the mate- 

 rial. Two steady-pins are inserted in the shaft, and jn-oject into 

 holes drilled into the coupling-boxes, to provide against negli- 

 gence in setting up the screw, thereby allowing the shaft to turn. 



This is evidently a valuable and efficient coupling. It presents 

 no nuts or bolt-heads to catch belts or clothing, obviates the neces- 

 sity of keys and splining, cannot get out of order, and presents a 

 neat appearance, when turned and polished looking nearly like 

 the enlargement of the shaft. 



This invention was patented April 24, 18G6, by S. P. Ruggles, 

 Boston, Mass. — Scientific American. 



