[ 496 ] 



. meat of the faire fpzce the next morning, when, being left out on purpofe, they 

 had contraftcd all the humidity they could, p. 439, 440. Defcription of the 

 fi'hifs rod?, ultimately ufed to determine the length of the bafe, tab. XIX. p. 441 — 

 449. The cafe containing the tube defcribed, p. 441. Manner in which the middle 

 or the tube is made fall to the middle of the cafe, p. 442. Fixed and moveable ends 

 of the tube aefcribed, p. 443. Fixed and moveable apparatus defcribed, p. 444 — 447. 

 IVIahogany lid on the top of the cafe defcribed, p. 447. Method of afcertaining the 

 length of the glafs rods, p. 440. Difpofuion ot the Hands for the double meafurement 

 with the chain and glafs rods; defcrijnionof the apparatus then applied to the ends of the 

 chain ; and ulcimate continuation of the medfurement witb the glafs rods alone, tab. 

 XVil. and XIX. p. -449- Reafons for rejedling the deal rods, ibid. Commencement 

 of the operation for the double meafarement, p. 450. 455. Apparatus attached to the 

 Hrll end of the chain, p. 451. Ditto for the lall end (to the right-hand fide of tab. 

 XVII.), p. 452. Comparifon of thecontraflionof fteel and glafs, with the error of the 

 chain in defe6t, p. 454. Farther experiments with the chain given up, and why, p.45^. 

 His Majefty honours the operation with his prefence, p. 456. Equation of the deal rods 

 and of the glafs rods, on 3 1 00 feet, ibid. Difference over-rated in the expanfion of the 

 ^60 deal rods, p. 457. Meafurement with the glafs rods completed, p. 458. Equa- 

 lionof the 1370 deal rods and of the 1370 glafs rods, with the difference over-rated in 

 the total expanfion of the deal rods, p. 459. Conjecture concerning the caufe of the 

 eftimated and real expanfion of the deal rods, ibid. p. 460. Defcription of the mi- 

 crofcopic pyrometer, ufed for determining by experiment the expanfion of the metals 

 concerned in the meafurement of the bafe, tab. XX. p. 461 — 472. The microfcopic 

 pyrometer (tab. XX.) defcribed, p. 462 — 472. Ufe and defcription of the fixed 

 microfcope, p. 466. Ditto of the micrometer, p. 467. Ufe of two eye glaiTes ia 

 microfcopes, p, 468. Scale of the pyrometer explained, p. 469. Account of the 

 experiments with the pyrometer, p. 472 — 476. Ultimate determination of the bafe 

 on HounUow-Heath, p. 476 — 478. General table of the bafe, fhewing the relative 

 heights of the llations above the fouth-eall extremity near Hampton Poor-houfe, the 

 leduftion of the hypothcnufes, and the correilion for the temperature of the glafs 

 rods, whereby the true length is obtained in the heat of 62 degrees, p. 479. Table 

 of the expanfion of metals, deduced from experiments made with the microfcopic 

 pyrometer in 1785, p. 480. 



BlaS, Mr. See Specific Gravities, 



Bnuguer. See Specijic Graviiies. 



Breedo7i, Leicefteriliire, obfervations on the lime-mountain there, p. 4. 



Brook.^ Mr. See Vacuum. 



Bruce, Robert, M. D. See Avtrrhoa Caramhla, 



Burning Mountains. See Morne Garou^ Caribbce IJIands* 



C. Cahknvoodj 



