CLOCK, 



of Wales, Pall Mall, declares, that lie 

 remembers a tubular pendulum to have 

 been u.. le by Mr. Finney, a well 

 known clock-maker of Liverpool, up- 

 wards of forty years ago, and that it is 

 now in the possession of Mr. De Mem- 

 bry, of Richmond, but time will not per- 

 mit the farther investigation of this point 

 at present. 



The last modification of the longitu- 

 dinal compensation made public is that of 

 Mr. Troughton, mathematical instrument 

 maker; it differs from Chandler's tubular 

 pendulum, in having- but two tubes of 

 brass, which afford the ascending com- 

 pensatioiiSjVvhile the descending' ones are 

 performed by five wires of steel. The 

 order of brass and steel is the same as in 

 Chandler's pendulum ; but all the steel 

 wires pass downwards through the inter- 

 nal brass tube. The last pair of wires 

 connect the whole with the bob by a 

 short cylindrical piece of brass, to which 

 the bob is suspended by its centre. 



Mr. Troughton made this pendulum 

 in July, 1804, and published the first 

 account of it in December same year, 

 in Nicholson's Philosophical Journal : we 

 believe he knew nothing of the priority 

 of Chandler's tubular pendulum to his, 

 and that, in thinking and declaring him- 

 self the first inventor of tubular pendu- 

 lums, he only fell into an error common 

 to many other ingenious men on similar 

 occasions; and this error is the more 

 excusable, as, at the time Chandler made 

 his pendulum, there were no periodical 

 works in existence, which professedly re- 

 corded the improvements of arts and ma- 

 nufactures, and artists were in general 

 more careful to conceal their discoveries, 

 than to acquire reputation by making 

 them public. 



Before concluding the enumeration of 

 various sorts of pendulums, one suggest- 

 ed by Mr. Troughton should be noticed, 

 which seems worthy of trial. He pro- 

 poses that its rod should be made of bak- 

 ed potter's earth, of the same cornposi. 

 tion of Wedge wood's thermometer, and 

 furnished with a metallic cap, by which it 

 should be sustained by the knife-edge 

 suspension, which the celebrated Ber- 

 thoud affirms has less friction than the 

 xprmg suspension 



The chief advantages which tubular 

 pendulums have over those of the grid- 

 iron construction are, that they admit of 

 being much lighter above the bob, with 

 eqral strength; that they experience less 

 resistance from the air in their vibrations; 

 '.hat they are less liable to those 



shakes and irregular motions in then- 

 expansions which the others experience: 

 on the other nand, as the outside tube 

 alone in them comes in contact with the 

 air through which it passes in its vibra- 

 tions, the inner tubes can receive much 

 less of its influence as to temperature 

 which arises from this motion, and which 

 Cummings has shewn to be of considera- 

 ble consequence. In Troughton's pen- 

 dulum the great difference of the masses 

 of matter between the ascending and de- 

 scending parts must be another source of 

 error, as the small wires of which the. 

 latter consist will indubitably much soon- 

 er experience the influence of a change 

 t>t temperature in the air, than the more 

 bulky substance of the tubes. In this lat- 

 ter respect Chandler's tubular pendulum 

 seems superior to Troughton's,all its parts 

 being much more nearly of the same mag- 

 nitude. 



More accurate comparative trials be- 

 tween these gridiron and tubular com-* 

 pensating pendulums, than any which 

 have yet been made, seem, however, ne- 

 cessary to determine the superiority of 

 either ; and the preference which many 

 are now inclined to give the tubular con- 

 struction seems more to arise from the 

 greater neatness of its appearance, than 

 from any sufficient experience of its high- 

 er merit. 



That it may be superior is very possi- 

 ble: we only aver that this has not been 

 yet proved. But if equal apertures were 

 made at both sides of tubular pendu- 

 lums, through ail the tubes, it would ob- 

 viate the chief objection to them, by ad- 

 mitting the air to act on all their parts at 

 once. 



Jn the year 1803, the Society for the 

 Encouragement of Arts gave a premium 

 of 20 guineas to Mr. Massey, of Hornley, 

 in Staffordshire* for a new striking part 

 of a clock ; the principal difference in 

 which from the common movement was, 

 that a pendulum about nine inches long-, 

 and which therefore vibrated pretty near- 

 ly half seconds, was used to regulate tlu 

 interval of tune between the strokes, in- 

 stead of the common fly wheel. Tin 

 other parts of tiie mechanism were also 

 of a simpler construction than those of 

 the striking parts of the clocks in com 

 mon use. 



Mr. Prior, of Nessfield, in Yorkshire, 

 also obtained a premium i'rom the above- 

 mentioned society, in the same year, of 

 30 guineas, for another contrivance for 

 the striking part of a clock; of which tin- 

 advantage consisted in the .simplicity ol 



