ON THE KEW OBSERVATORY. 341 



H, &c. of fig. 3, or it may be placed in any high situation on the earth, at a 

 distance from buildings, &c., and a long wire may be attached to a stronger 

 and shorter rod taking the place of D. This wire may communicate with 

 internal apparatus, and thus Beccaria's principal method of observing the 

 electricity of serene weather, dew, &c. may be adopted and compared with 

 others, and with the electricity of higher strata of the atmosphere. 



Or (much better), several such insulators may be distributed over a con- 

 siderable space and made to support several wires connected with each other 

 and with the internal apparatus. 



A large network of small wire thus insulated has long been a desideratum 

 with me. The pillar F, &c. miglit be inclined for tlie sake of acquiring a 

 better position for resisting the weight of such network. 



For examining the electricity of rain in Cavallo's manner, a hoop of copper 

 supporting a net work of wire, as shown by the dotted lines, might be ad- 

 vantageously substituted for the above-mentioned dish or the conductor D, 



Three such insulators might be placed in an equilateral triangle, and 3 

 light cords, containing very fine wires, might be attached to an electrical 

 kite, thus maintained at a nearly invariable height, as was done by lines not 

 wired, in a rough experiment made here in 18'17, with a view to temperature 

 and hygrometric observations (vide Phil. Mag. for September 1847). 



The Photo-Electrograph remains nearly as described in the Phil. Trans. 

 Part I. for 1847. It will be improved by the addition of a little apparatus 

 applicable to the registration of electrical frequency, and removed into the 

 Dome. 



Anemometer, &c. 



The Wind-Vane xema.ms as described in the Report for 1844, p. 129. 



The Balance Anemometer of metal — an improvement upon that described 

 in the Report for 1844, p. 129, and precisely similar in principle, but 

 more sensitive — will be particularly described when further contemplated 

 improvements have been effected. It is supported upon either a pillar at- 

 tached to the northern part of the balustrade of the leads, or upon one at the 

 southern part, according to the direction of the wind. It turns to the wind 

 on hard steel centres, and vibrates vertically upon hard knife-edges and 

 rings, in the manner of a delicate scale-beam. 



Rain Gauges, &c. 

 The Rain- and Vafour-Gauge is in the state described at p. 129 of the 

 same Report. Wear does not seem to affect its sensibility. On November 

 16, 1850, it was removed from the support of the old rain-gauge and placed 

 upon a strong tripod, very near to its former locality, viz. the southern end 

 of the leads, and at the same height as before. 



The old Rain-Gauge is a relic of His Majesty George the Third's col- 

 lection of Kew instruments. Its aperture is a square foot. A bottle, the 

 neck of which nearly fits the conducting-pipe, is placed beneath it, and a 

 glass cubic-inch measuring vessel is used (in Howard's manner) to ascertain 

 the amounts of rain. 



Thermometers, Hygrometers, &c. 



The Thermometer-stand(P]ate XIX.), not before clearly described, and nearly 

 similar to that of Greenwich, is situated in front of the northern entrance on 

 the stone platform. The mean distance of its face from the wall (or door) 



