NEGRETTI AND ZAMBEA, HOLBORN VIADUCT, E.G., 



the Royal Navy and for the observations made at sea for the Board of Trade 



and Meteorological Department. 



Price, in Neat Japanned Case 10 6 



Ditto Copper Case 12 6 



A set of 6 Ditto ditto, in Copper Cases, fitted in a Mahogany Box . 2 10 



41. Thermometers of Extreme Sensitiveness. Negretti and Zambra's 

 Instantaneous Thermometer, with Gridiron form of bulb, and divided upon the 

 stem, as shown in the International Exhibition of 1862, used by Mr. Glaisher in 

 his Balloon ascents to obtain very rapid thermometric readings. 

 (Fig. 35) Price, 3 3 to 6 60 



42. Thermometers, very delicate, with Spiral or 

 Coiled bulbs, engine-divided upon the stem, mounted on 



boxwood, metal, or opal glass scales. Fig. 36. 



Price, 220 and 330 



43. Earth Thermometer for ascertaining the tem- 

 perature of the soil at various depths. The tube is about 

 five feet long, enclosed in stout wood, protected and 

 strengthened by metal mountings and a pointed cap. 

 The scale is of Negretti and Zambra's Patent Porcelain 

 with enamelled and burnt-in divisions and figures. 

 Figs. 37 and 38. Price, 1 15 and 220 



44. Earth Thermometers in series for inserting into 

 the ground at depths of 6 inches, 12 inches, 24 inches, 48 

 inches and 120 inches. These thermometers are arranged 

 with a scale about 6 inches above the earth. 



Price for the series 7 7 



45. The temperature of the soil is a very important 

 element in the consideration of climate especially in 

 connection with the growth of vegetation. " It has been 

 calculated by Mr. Raikes, from experiments made at Chat 

 Moss, that the temperature of the soil when drained 

 averages 10 higher than it does when undrained ; and this 

 is not surprising when we find that lib. of water evaporated 

 from 1,000 Ibs. of soil will depress the whole by 10, 

 owing to the latent heat which it absorbs in its conversion 

 into vapour." 



Faraday has calculated that the average amount of heat 

 radiated in a day from the sun on each acre of earth in the latitude 

 of London, is equivalent to that which would be produced from 

 the combustion of thirteen thousand four hundred and forty 

 pounds of coal. 

 FIG. 38. " The extremes of temperature in the different climates of the 



FIG. 37. 



