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Mr. SHuman: Of course, that is what is always desired. I 
believe every steam engineer, if hie could, would go in for 
electricity. But turning heat into electricity is a costly thing, 
and it does not pay. We have done it by putting up a plant 
with little thermopiles, which turned the sun’s heat directly 
into electricity, and every heater might be so constructed. But 
when we attempt to do that every square foot of surface costs 
about £10 sterling, which is, of course, out of the question 
altogether. We have to keep down to a matter of 2s. or 3s. 
per square foot. 
Mr. A. S. E. Ackermann: Mr. Chairman and Gentlemen— 
I have been greatly pleased to be associated, in conjunction 
with my colleague, Mr. C. T. Walrond, with the interesting 
work of Mr. Shuman and his enterprising clients, the Sun 
Power Company, the directors of which are to be congratulated 
for the plucky manner in which they have spent large sums of 
their own money in the experiments. When I first heard in 
June, 1910, of water being boiled by the unconcentrated 
radiation of the sun I was very incredulous, but on arriving 
in Tacony, a suburb of Philadelphia, I found that the small 
sun heat absorber (consisting of a lamellar boiler in a flat box 
with a cover formed of two sheets of glass with a I-in. air 
space between them) was, in fact, boiling water without any 
concentration by mirrors or lenses or any other means. The 
maximum temperature which I registered under the second 
layer of glass was 250° F. 
There were practically no mechanical difficulties in con- 
nection with the utilization of solar energy; it was merely a 
question of either reducing the cost of construction of the 
plant, or of increasing its output per square foot of radiation 
collected. The improvement effected by the design of the 
Egyptian plant compared with that at Tacony was that 
the former gave 33 per cent. more steam than did the latter. 
Part of this was no doubt due to the improved climatic con- 
ditions in Egypt, but it was equally certain that part was due 
to the improved design, for on comparing the atmospheric 
conditions which obtained during the Tacony trials with those 
which obtained during the Egyptian trials, the difference was 
found to be small. 
Another important improvement in connection with the 
Egyptian plant was that the output of steam was much more 
nearly constant than that of the Tacony plant, and was more 
constant than was expected. This was due to the fact that 
the number of solar rays caught in the morning and evening 
was the same as that caught at mid-day, the only difference 
being that in the morning and evening the radiation passed 
through a thicker layer of atmosphere. For irrigation purposes, 
