N.B.-Some of the above Chemical Preparations varying continually in price, E. P. cannot pledge himself to be confined at all times to the Catalogue quotation, but will, in such cases, charge as low as possible. Fig. 62. Fig. 63. DIRECTIONS FOR USING THE PORTABLE Having placed it in an upright position, unscrew the small head at top of righthand tube A, as far as possible, and turn the stopcock B; the mercury will then be observed to fall, and should be allowed to remain a short period of time to settle at the correct temperature. When about to make an observation, place the arrow on the Barometer scale to the surface of the mercury in the right-hand tube, and observe the temperature by the Thermometer; then place the point of the vernier in the same degree on the Barometer tube as the mercury stands in the Thermometer, which will indicate the weight of atmospheric pressure precisely the same as any other Barometer. To make the instrument portable, gently incline it downwards, and when in that position, turn the stopcock off and screw the brass head at A, until it feels sufficiently firm. 9-inch ivory-scale Thermometer, on ebony, with German. silver mountings 10-inch jointed ivory-scale Chemical Thermometer, in mo rocco case 8-inch metal-scale Thermometer, in japanned case, for Brewing, &c. &c..... 0 0 10 0 ...... 0 14 0 Large Brewing Thermometer with metal scale, in copper case 0 15 4-inch metal-scale Thermometer, in morocco case 6-inch ditto ditto.... Day & Night self-registering Thermometer, with boxwood scale, 15s. Day & Night Oval Thermo 111 Fig. 66. very superior Fig. 67. 10-inch ivory- meter, with copper roof, Fig. 63. meters, for portability, in boxwood, 9s. 6d. Ditto ditto, ivory, 12s. 8-inch ivory-scale Window Thermometer, with mahogany frame and glass cylinder |