194 
below zero. The snow had just fallen, and the air was very 
clear. 
The reason the world is colder in the winter than in the 
stummer is not because the sun is not so hot; the sun is in 
reality hotter, but owing to the angle at which his rays strike 
the earth we get less benefit from them. For instance, in 
England the sun’s rays strike the earth in winter at an angle 
as low as 35°, so that the rays are spread over a much 
larger surface, consequently we have much colder weather. 
But when you turn a surface directly towards the sun, as we 
do our heaters, then you get more heat in the winter than in 
the summer. Therein lies the difference between our heaters 
and the earth’s surface in general; in the former case the effect 
is one of concentration, in the latter of diffusion. 
Mr. P J. Burcess: If you are going to adapt your sun- 
power plant to places outside the tropics, it will be necessary 
for you to tilt your sun-catching machine, will it not? 
Mr. SHuman: If we were to put up a sun heater here we 
would not turn the apparatus from north to south, but from 
east to west. 
Mr. Burcess: You would have to have a movement in both 
directions. 
Mr. Suuman: We would prefer very much to have a move- 
ment in both directions, because we would get a better result 
in that case. But as the practicability of this system depends 
upon the yield of power per pound sterling invested, we have 
to throw that extra advantage away because, if we attempted 
to do that, our sun heater would cost so much more. If we 
had to turn it in both directions, it would mean such -compli- 
cated mechanism that it would not be practicable. 
Mr. Burcess: Is not that a consideration which practically 
precludes the possibility ? 
Mr. Ssuman: No, I would not propose a sun heater at the 
North Pole, or in unreasonable places, but I was speaking just 
now of Indian conditions in winter. That was the question 
which brought up this discussion. The sun in winter in the 
tropics is by no means so low as in India. I do not know 
exactly the latitude of that portion of India which was referred 
to just now, but I imagine the sun would still be at a fairly 
steep angle in winter, and that would make the use of a sun 
heater quite practicable. 
Mr. Burcess: One more question. As I understand. this 
sun-power plant catches the heat of the sun, turns it on to the 
water, turns the water into steam, and the steam is made use 
of in the usual way. Is there no way of turning this sun heat 
directly into electricity? Steam is becoming rather an anti- 
quated form of power now. Could we not turn the heat 
directly into electricity ? 
