March 20, 1885 ] 



. KNOWLEDGE • 



2.13 



Xight Sign for Marcli, 



watching their appearance for some time, I drove over to 

 Ciptain Noble's observatory, about five miles off, and fuuiid 

 that his telescope did not exhibit anything of the kind. 

 The road being very hilly, and some time being spent with 

 him, I did not get home till some two hours after starting, 

 and still the light showers were visible. The total quantity 

 must have been very large, atid nothing could be thought 

 of Eo likely as thistle-down to have produced the pretty 

 effects. 



The pappus hairs of the Composites are . usually the 

 most interesting parts for microscopic observation, though 

 the seed itself — as in the Cornflower — is often beautiful. 

 In many other families the ffgta, or external membrane, is 

 decorated with fine markings, and the seed may be of 

 curious shape. Hairs, scales, pits, rib,", Ac, vary the 

 aspects of those represented in Carter's collection, to which 

 it is profiosed to return on other occasions ; but as variety 

 is desirable to suit various tastes, the next paper will be 

 on quite another subject — the so-called molecular, or 

 Brownian, movements of small particles suspended in 

 fluids. In this matter there is still room for fresh investi- 

 gation. 



The Electric Lighting Act. — At a meeting of the General Com- 

 mittee formed to frame amendments of the Electric Lij^hting Act, 

 1882, for the consideration of the Board of Trade, held at the 

 Offices of the Anglo-American Brush Electric Light Corpt ration, on 

 March 11, Lord Thnrlow presiding, the report of the Executive 

 Committee and a Draft Bill amending the Electric Lightii,g Act, 

 1882, on the basis of the Gas Acts, were submitted. The details 

 having been explained, it was resolved unanimously, on the motion 

 of Tiseonnt Anson, that the report of the Executive and the Draft 

 Bill be approved. The Chairman was asked to communicate with 

 the President of the Board of Trade with a view to a deputation 

 attending to learn his views on the proposals of the Committee. 



ZODIACAL MAPS. 



IN fiilfilment of the promise given on p. 189, Ve repeat 

 here the Night Sign for March, thus completing the 

 series of twenty-four Zudiaoal Maps. 



THE PHILOSOPHY OF CLOTHING. 



By W. Mattieu Williams, 

 IV.— THE COOLING ACTION OF THE SKIN. 



THE question suggested by some of the facts stated in 

 my last is, How is the t'iiiiperature of the body kept 

 down when it ia surrounded with an atmosphere saturated 

 with vapour, and considerably above blood heat 1 We 

 must always remember that superficial evaporation only 

 takes place when the surroundiug air is not already sup- 

 plied with its full ((uantity of the vapour in question. In 

 this case it is the vapour of water to the formation of 

 which the whole work of cooling the body is usually 

 attributed. 



If no other gaseous matter than aqueous vapour — i.e., 

 water in the gaseous form — were given oft' from the skin, 

 I should say " give it up " to this piiysiologioal riddle ; but 

 such is not the case. Other gases accompany the gaseous 

 water, and, if those gases are evolved by the expansion of 

 bodies that were previously in a solid or liquid condition, 

 this evolution can only be effected at the expense of much 

 sensible heat by a lowering of temperature proportionate 

 to the amount of the expansive woik performed. 



Spallanzani, Abernethy, Milly, Jurine, Ingenhous 



