45, COBNHILL, E.G., AND 122, REGENT STREET, W., LONDON. 497 



PHOTOMETERS FOB TESTING ILLUMINATING POWER OF 



COAL GAS. 



& s. a. 



3074 Glass Tube Pressure Gauge, with 6-inch Glass Syphon, with 



Stopcock, ivory scale, best finish 14 . 



3075 Ditto ditto large size 12-inch Scale, best mounted . . 1 10 



3076 Gas Inspector's Gauge, with best fittings complete, in Leather 



Pocket Case (see also page 197) 220 



3077 Sensitive Gas Thermometers, 5-inch Ivory Scale, with projecting 



bulb for taking temperatures in gas mains, in Pocket Case . 10 6 



3078 Bunsen's Photometer, for comparing and measuring the illuminating 



power of coal gas, and for testing the comparative value of 



various gas-burners . . . . . . . . .330 



3079 Dr. Letheby's 60-inch Photometer, mahogany standards, gas pillar, 



with double cock, micrometer adjustment, slide for candle, 



wooden shades, &c 880 



3080 Evans' Standard Photometer, 100-inch scale, in polished pine case 



lined with black velvet, with disc frame, central adjustment, slide 

 ventilators, velvet canopy, &c., &c. 17 17 



3081 Experimental Meter, 144 cubic inches capacity, combination index, 



minute clock and gas index working on one dial, 5 feet hourly 

 rate of consumption, and time circle, small circles showing 5 feet 

 actual consumption, and 10 minutes. The minute clock with 

 lever escapement dead beat provided with bell, which is struck 

 every minute . . . . . . . . . . . 12 12 



3032 Sight-hole Beam, or brass cross-piece pillar, with brass chains and 

 weights, scale for weighing two candles in candle holders whilst 

 burning, grain weights 500 to i-grain, mounted on mahogany 

 board 500 



3083 King's Pressure Gauge, to show 100th part of an inch pressure, 



3 3s. 4 4 



3084 Specific Gravity Apparatus, for testing the gravity of Coal or other 



gases, consisting of a light glass flask of one Cubic Foot capacity, 

 mounted with a Stop-cock and also a suitable Balance and grain 

 weights, one grain being equivalent to 1'728 cubic inches of air .330 



3085 Jet or Inferential Photometer (Lowe's), for testing and comparing 



the illuminating power of gas . . . . . . .440 



3086 Testing Gas Holder, of 2 cubic feet capacity, with copper bell, 



double divided scale, balance wheel or friction rollers, cycloid 

 and weights, gun metal taps, pressure gauge, &c., &c., complete 

 for laboratory service , . . . 21 



3087 Ditto ditto of larger size, with more finely divided scales and 



adjustments for testing meters 40 



FOR GAS PRESSURE GAUGES, GAS TESTING THERMOMETERS, GRADUATED TUBES, 



SPECIFIC GRAVITY FLASKS, HYDROMETERS, &C., &C., 



SEE PAGES 153, 167, 176, 196, 206 AND 375. 



2 K 



