24 



PRESIDENTIAL ADDRESS SECTION A. 



science, but the alluring problem of utilising directly the sun's 

 heat as a source of energ_v, and constructing a commercially suc- 

 cessful solar motor, has so far baffled all inventors, although it 

 has brought much grist to the mill of the patent agent. 



It has been calculated that the solar energy is equivalent to, 

 80,000 h.p. per sq. yard of the surface of the sun. If there were 

 no absorption, Professor Fleming has calculated that the earth 

 would receive the equivalent of 250 x 10^- h.p., but owing to 

 atmospheric absorption, clouds, and obliquity of the rays, the 

 actual amount absorbed at the earth's surface is only 4 per cent. 

 to 10 per cent, of the solar heat delivered. Investigations, car- 

 ried out by Professor \'ery. led him to conclude that the amount 

 of solar energy received per annum at the earth's surface, on an 



Fk;. 2. — Sliuinan's Sfilar Plant. Earlier Tvnc. 



area of 100 s(|. metres, was equivalent, at the places iiuh'catcd, 

 to— 



K.\\'. 

 Central Europe 4 to 6 



Northern United States 

 S.\A\ United States 



5 to 7 



10 to T ; 



hours. 



millions. 

 3 millions. 



millions. 



In his Royal Institution Lectures in igii. Professor I. J. 

 TTiomson, the well-known i)hysicist, stated that, shining from a 

 clear sky. the sun send to the earth, energy at the rate oi 7.000 

 h.p. per acre. 1'his energy would be the heat e(|uivalent of 

 2^ feet thick l)c'(l of coal formed every vear. 



But even tiie most ardent advocate of the solar engine does 

 not claim that it is ])racticable. except in the tropics, and even 

 then commercially impossible unless coal is at least £3 ])er ton. 



(h^G of the earliest \v(M-kers in this field was Captain h)hn 

 Ericcson. who wc)rl;ed ])ersistc'ntl\ from 18^3 to 1S7S. and 

 Tun'lt in that time seven sun motors, ihe method adojited bring to 

 concentrate the sun's rays on a boiler, b'ventually lie succeeded 

 in obtaining about I h.p. for every 100 sq. feet of absorbing sur- 

 face, but finally abandoned his eltorts as commercially impracti- 

 cable. " The fact is." he admitted. " that, although the heat is 

 obtained for nothing, so expensive, costl\'. and complex is the 



