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The Museum Gazette 



leaves, &c. You must not suppose, however, that all the serpentine 

 mines are those of Nepticula. There is a long serpentine, or some- 

 what serpentine one to be found in leaves of cherry, apple, &c, caused 

 by Lyonetis clerckella. The very numerous blotches on laburnum 

 leaves are caused by Cprneostoma laburnclla, and the pupa may often 

 be seen in its silky cradle among the leaves and branches, the imago 

 comes out in the months of May and August. 



The Lithocolletis may be bred by collecting the mined leaves and 

 putting in rather small corked bottles, but as they do not come out 

 until May there is a difficulty in preventing their becoming mouldy on 

 the one hand or too dry on the other. The easiest way of breeding 

 a species of Lithocolletis to see what it is like, is to collect L. 

 riienaniella mines in April and botile them as I have said ; the imago 

 will appear in May or earlier if in the house, and hence somewhat 

 warm. 



Radium and the Possible Duration of Time. — ''Radium has been 

 proved to give out enough heat to melt rather more than its own 

 weight of ice every hour ; enough heat in one hour to raise its own 

 weight of water from the freezing-point to the boiling-point. After 

 a year and six weeks a gramme of radium has emitted enough 

 heat to raise the temperature of 1,000 kilogrammes of water one 

 degree. And this is always going on. Even a small quantity of 

 radium diffused through the earth will suffice to keep up its tempera- 

 ture against all loss by radiation ! If the sun consists of a fraction of 

 one per cent, of radium, this will account for and make good the heat 

 that is annually lost by it. 



"This is a tremendous fact, upsetting all the calculations of physi- 

 cists as to the duration in past and future of the sun's heat and the 

 temperature of the earth's surface. 



"The geologists and the biologists have long contended that some 

 thousand million years must have passed during which the earth's 

 surface has presented approximately the same conditions of tempera- 

 ture as at present, in order to allow time for the evolution of living 

 things and the formation of the aqueous deposits of the earth's crust. 

 The physicists, notably Professor Tait and Lord Kelvin, refused to 

 allow more than ten million years (which they subsequently increased 

 to a hundred million), basing this estimate on the rate of cooling of a 

 sphere of the size and composition of the earth. They have assumed 

 that its material is self-cooling. But, as Huxley pointed out, mathe- 

 matics will not give a true result when applied to erroneous data. It 

 has now, within these lasi five years, become evident that the earth's 

 material is not self-cooling, but, on the contrary, self-heating. And 

 away go the restrictions imposed by physicists on geological time. 

 They are now willing to give us not merely a thousand million years, 

 but as many more as we want." (From the inaugural address, York 

 Meeting of the British Association, by Professor E. Ray Lankester, 

 F.R.S., President of the Association, Nature, Augiist 2, 1906.) 



