OF MECHANICAL AND DYNAMICAL APPARATUS. 205 



2376. Model Apparatus for Exhibiting the Mechanical Powers, viz., levers, simple 



and compound, pulleys of various kinds, inclined plane, wheel and axle, screws 

 of various sizes and pitch, capstan, wedges, etc., in mahogany and boxwood ; 

 in case, with weights, 1 Is., 3, and . . . 500 



2377. DITTO, DITTO, more highly finished, and complete with brass pulleys, etc. 



10 7s. to . . . . . . . 15 10 



2378. SET OF LEVEES, mahogany, of the first, second, and third orders and bent form, 



on stand, with friction rollers and graduated scales, 1 Is. to 1 10 



2379. SET OF LEVEES, in brass, 4 and . . . . 4 10 



2380. A SET of three-toothed wheels and pinions, for showing the relation of power to 



weight . 1 16 



2382. SET OF COMPOUND LEVEES, in wood, with stand, 1 ; ditto, in brass 4 10 



2383. SETS OF PULLEYS, for making different combinations, 3s. to . 10 



2384. A Set of Three Brass Pulleys, in frame, of the first, second, and third orders 



1 18 



2385. A PAIE OF THBEE-INCH WHITE'S PULLEYS, 1 16s. ; ditto, of 6-inch 2 12 6 



2386. INCLINED PLANE, 24-inch., with locomotive, and graduated arc of 90 degrees, to 



explain the law of gradients, and showing that an angle of 10 degrees increases 

 the resistance of the load nine times . . . . 3 15 



2387. INCLINED PLANE, niahogany, with graduated arc and roller, for increasing or 



reducing the angle, 10s. 6d. to . . . . 1 10 



2388. Models, to show the principle of the screw and nut, to illustrate the action of 



screws of different degrees of inclination, the compound and endless screw, 15s. 

 to ..... 1 5 



2389. FEEGUSON'S COMPOUND ENGINE, in which all the simple mechanical powers 



move together . . . . . . 4 10 



2390. A SET OF Six BEASS VALVES, highly finished, on 4-inch, mahogany blocks, 



showing the flat, clack, conic, ball, throttle, and side valves . 2 2 



2392. DITTO, DITTO, of 5, viz., the butterfly valve, bellows valve, round spring valve, 



conical valve, and oil-silk valve, in stained hard wood, each 6 inches in dia- 

 meter, the set . . . . . . 10 6 



2393. Whirling Table, improved form, as adopted in the military schools, for de- 



monstrating the laws of planetary motion and central forces, including the 

 Keplerian law, etc. ...... 13 10 



2394. WHIELING KINGS, for proving the oblate figure of the earth . 110 



2395. APPAEATUS to illustrate the centre of gravity, consisting of 2 equal parallelepi- 



peds of a rhomboidal form. They stand firmly on end when separate, but fall 

 when placed on one another . . . . 2 



2396. LEANING To WEE OE OBLIQUE CYLINDEE, in 2 pieces. They stand firmly on 



end when separate, but fall when placed on each other . 020 



2397. AN IEEEGULAE BOAED, with 2 strings attached, with lines drawn to show how 



the centre of gravity of an irregular surface may be found . 1 6 



.2398. SEMICIECLE of brass, weighted at the two ends, supported on a brass stand, with a 



knife edge, to show the centre of gravity . . . 036 



