196" CATALOGUE. — PHriOSOPHY AND ARTS, PRACTICAL MECHANICS. 



Academy of Petersburg, calculates, that according to theory, 

 -it ought to have lost 2" only. But Bernoulli's theory ap- 

 pears to be erroneous ; he says, that the compound vibra- 

 tions can only exist in such a manner that the point of sus- 

 pension shall move in a direction opposite to that of the 

 weight. Nicholson asserts, with more apparent truth, that 

 the vibrations are more rapid as the fulcrum is firmer. The 

 fulcrum must not be considered as a weight, but as a por- 

 tion of an elastic substance. 



Sandglasses. 



Lahlre's new hourglasses. A. P. X. 472. 

 Prospei's hourglass. A. P. 1727. H. 143. 



Mach. A. V. <i3. 

 Soumille's sandglass of 30 hours. S. E. 1. 80. 

 Sand is said to flow equably. Cooke. Ph. M. 



XII. 312. 

 Gould's patent log glass. Rep. ii. III. 242. 



Measures of Time not simply me- 

 chanical. 

 See Hydraulics and Practical Astronomy. 



Bernoulli on marine clepsydras. A. P. Pr. 



1.4. 

 Duguet's clepsydra. Mach. A. VI. 131. 

 Arderon on the weaver's alarm. Ph.tr. 1745. 



XLIII. 555. 



A candle burning a thread passed through it. 



Hamilton's clepsydra. Ph. tr. 1746. XLIV. 

 171. 



Supplied from a cistern running over. Too complex. 



Enc. Br. Art. Chronometer. 



The motion of air, the consumption of oil, and the burn- 

 ing of a candle may be employed as measures of time. 



King Alfred is said to have used six wax tapers burning 

 in a lantern. Hero's clepsydra was a siphon, supported by 

 a float, and bent over the side of the vessel. 



Raising Weights in general. 



Leup. Th. M. G. Th. Machinarium. 



Hydraul. Th. Hydrost. t. 18. 29. 

 Belidor. Arch. hydr. I. i. 25. 



Th. 



Loriot on raising weights by the tide. A. P. 



1761. H. 1,59. 

 A fire ladder. A. Petr. I. i. H. 67. 



Supporting itself. 



Brooks's buoyant machine for raising weights. 



Repert. VII. 36I. 

 Harriott's engine for raising and lowering 



weights by water. Nich. 8. IV. 41. 



Levers. 



Levers. Leup. Th. Machinarium. t. I6. 



Levers on a large scale. Leup. Th. Hydrot. 

 t. 11. Th. Hydraul. I. t. 56. 



Compound Levers. Leup. Th. Machinarium. 

 t. 17. 18. 



Levers with ratchets. Leup. Th. Machina- 

 rium. t. 17. 



"t-Emerson's niech. f. 186. 



Liftingstock, a lever with a double fulcrum. 

 Emers. mech. 29.5. 



Lever with a counterpoise, for raising a 

 bucket. Musschenbr. Introd. I. PI. 5. 



Lever with ratchets. Musschenbroek. Introd. 

 ■ PI. 6. 



Mrs. Wyndham's lever. S. A. XIV. 296. 

 Repert. VI. 246. 

 With a cross bar. 



Wheel and Axis. 



Lahire. A. P. IX. 90. 



Debelloy on reducing the weight of chains 

 and ropes. Roz. XXXII. 375. 



Observes, that if they are to be always vertical, the lower 

 part may have its weight diminished. 



Featherstonehaugh's counterpoise to the chain 

 of an axis. S. A. XVII. 338. Repert. XH. 

 105. 



Capstans. 



Leup. Th. Machinarium. t. 19. 20. 

 Madelaine's capstan. Mach. A. II. 3. 

 3 



