378 Proceedings of the Royal Institution, 



large ; in 1700, it was about ^ of the whole population ; in 1801; >^ 

 was -f'^; in 1811 and 1821, it was -j^; the number of persons 

 coming annually from the country and settling in London had been 

 estimated at ^ the yearly deaths in the metropolis. The proportion 

 of deaths in the kingdom at large was stated to have considerably 

 diminished during the last century. In 1780, the proportion was 

 supposed to be about 1 in 40 ; in 1801, it was 1 in 47 ; in 1811, it 

 was 1 in 52 ; and in 1821, it was 1 in 58. The extreme duration of 

 life does not, however, appear to have increased. The proportion of 

 deaths in Pembrokeshire has been estimated as low as 1 in 83 ; and, 

 in another county, it had been found as high as 1 in 22 J ; in Russia, 

 it was stated as 1 in 41, but attended with many remarkable in- 

 stances of great longevity, there having died in 1828, 895 persons 

 between the ages of 100 and 120 ; and 53 between 120 and 160. 

 The relative mortality in summer and winter was stated to be about 

 as 57 to 72 ; and the difference of deaths, in the large towns and the 

 country, nearly as 2 to 1, The well-ascertained difference in the 

 duration of life among males and females was also pointed out, 

 that of the females being the greatest at all ages ; and it was shewn, 

 that, as a compensation for the greater mortality of males, the num- 

 ber bom, to the number of females, was very nearly as 20 to 19. 



Presents of geological specimens, from Ceylon, presented by Dr. 

 Davy, and numerous other things, were upon the Library table, on 

 this as upon all other occasions of these meetings. ^[ 3^'X 



April 2d. ^^ c:oi.TO<7 



Mr. Ainger, On the Theory of the Radiation of Heat. — The pur- 

 port of Mr. Ainger's observation was to explain one or two facta 

 connected with the radiation of heat, and the apparent radiation of 

 cold, which, though familiar to those who have studied the subject, 

 are by no means generally understood, and are unexplained ihdl^'^^ 

 English works upon this branch of science. ^ - . 



The experiment made by M. Pictet, of placing a piece of 16^ in 

 the focus of one mirror, and a thermometer in that of another, and 

 the explanation of the phenomena furnished by the hypothesis of M. 

 Prevost, are too well known to require more than a brief notice. The 



