1 1 2 Annals of the Philosophical Club 



saying that hitherto the difficulty of separating it from the 

 mass had much impeded a profitable development of the 

 metal. 



Colonel Sykes, at the 27th meeting (Feb. 28th), drew 

 attention to two sources of grave error in observations 

 with wet-bulb thermometers. These were (i) a possible 

 lowering of temperature by the proximity of a dry-bulb 

 thermometer ; (2) in calm air its own vapour, by forming an 

 enclosing shell, might make readings fallacious ; (3) if that 

 shell is removed by a current of air, the velocity of the 

 latter affects the temperature of the bulb ; (4) it is also 

 affected by radiation from surrounding objects ; (5) the 

 dew-point determined by Apjohn's formula, appears to 

 be too high with small depressions of the wet-bulb thermo- 

 meter, but much too low with considerable depressions. 

 The last matter he discussed in some detail. 



A letter from Dr. Layard, 1 read at the 28th meeting 

 (March 28th), announced the discovery of some new sculptures 

 in Assyria. Attention was called to" the importance of 

 securing daguerrotypes of all figures too heavy to be moved, 

 and this led to a discussion on photographic questions. 



The 29th (anniversary) meeting fell on April 29th, when 

 Mr. Spence referred to the exhibition of two flies at the 

 Zoological Society, apparently identical with a species 

 described by Bruce, the bite of which drove cattle mad, and 

 which seemed to have a resemblance to the Hornfly. 2 



The subject of photography was resumed, and Lord Rosse 

 remarked that Ronconi was reported to have daguerrotyped 

 some of the nebulae, but he doubted whether the light of a 

 nebula would suffice to produce a daguerrotype that would 

 be of any use, and whether an equatorial could yet be 



1 Afterwards Sir A. H. Layard, G.C.B. (1817-94). He was then, viz. 

 from October, 1849, till some time in 1851, working at either Kayunjik 

 or Nebi-Yunus, having begun excavations at Nimrud in 1845 and sent 

 to England, in the following year, the large man-headed winged bull and 

 lion, which are now, with other important pieces of sculpture, obtained in 

 this (see Nineveh and its Remains) and the later expedition, preserved in 

 the British Museum. 



2 Haematobia serrata, a pest to cattle in Abyssinia. 



