358 
NATURE 
[May 27, 1915 

combustion of illuminants. The Commission, so far, | spheric) pressure, an efficient engine for the use of 
has added a considerable amount of useful informa- 
tion and evidence confirmatory of the views held by 
physiologists in this country. 
The Commission points out how in the case of a 
school building the chosen architect strives to outdo 
the others in the size and ornamentation of the build- 
ing, and to satisfy the excessive requirements of the 
school committee. Then begins the process of trim- 
ming, and the heating and ventilating plant being 
the biggest single item of equipment, comes in for 
the most attention, with the worst results. And this, 
too, despite the fact that the ventilating, plant is 
really the lungs of the building, and counts most 
for the comfort and efficiency of the occupants. ** But, 
of course, there must be so many rooms, just so many 
gargoyles, and just so much marble. Fer these 
things are seen and read of all men.” 
THE UTILISATION OF SOLAR ENERGY}! 
ie the first part of the. paper referred to below are 
given particulars of the various apparatus which 
have been used to obtain’ power from solar radiation. 
In doing so the author was able to describe in fair 

such steam had to be designed, and in this Shuman 
was uniquely successful, for when. the author tested 
a Shuman low-pressure engine at Erith he found that 
its steam consumption was.only 22 Ib, of steam at 
16-2 Ib. sq. in. abs. per b.h.p. hour, the b.h.p. being 
94:5. This beats all the old atmospheric engines, and 
indeed everything to date for steam at that pressure. 
Shuman’s 1910 sun heat absorber had an area of 
only 15 sq. ft., and the tests made with it showed 
that at its best 300 sq. ft. of it would be required to 
produce enough steam for one b.h.p., allowing the 
aforementioned 22 Ib. per b.h.p. hour. 
In 1911 Shuman made another absorber like that of 
Ig10, except that it had two plane silvered glass 
mirrors, one attached to the upper edge of the ‘ hot- 
box?’ and one to the lower, and so arranged that 
2 sq. ft. of solar radiation were concentrated on to 
r sq. ft. of boiler surface. The hot-box (originated 
by H. B. de Saussure, the Swiss geologist, physicist, 
and naturalist, who died in 1799) was 3 ft. wide, 
6 in. deep, and 66 ft“ long. There were twenty-six 
Such sections.. The back was formed of 3-in. mill- 
board, on top of which was 2 in. of cork-dust, covered 
with 4-in. millboard. The laminar boiler (about 4 in. 

Fic. 1.—General view from the west of the Shuman absorber; Tacony, 1911- 
detail the construction of such apparatus, but he 
stated that he had been unable to get any but the 
most meagre information as to the results obtained 
with the various plants, and much of that appeared 
to be untrustworthy. The case was very different in 
regard to Shuman’s work since and including the 
year 1910, for the author himself had conducted the 
experiments with Shuman’s plants. 
Shuman set out with the idea that the principle of 
former workers in this field of using high-pressure 
steam was wrong. He argued that high-pressure 
steam meant a high temperature, and therefore a 
large loss due to radiation. We shall see later that 
though this is true, a better overall efficiency is 
attained when the steam pressure is higher and the 
boiler area is reduced, so as to save loss due to 
radiation. It is also a thermal advantage to have a 
high concentration of the solar radiation, but Shuman 
started first of all without any concentration (which 
has its advantages by reason of simplification); then 
he used a concentration of two to one, and finally 
4-6 to one. y 
As steam was to be generated at a low (say atmo- 
1 Abstract of a paper read before the Royal Society of Arts on April 28 by 
A. S. E. Ackermann. 
NO. 2378, VOL. 95| 

thick) was fixed in front of this, leaving an air space 
of an inch between it and the millboard. In front 
of the boiler was another air space of an inch, then a 
sheet of window-glass, another air space of 1 in., and 
finally the top sheet of window-glass. 10,296 sq. ft. 
of solar radiation were thus collected, and the best 
hour’s run gave 816 Ib. of steam at a pressure of 
14-2 lb. sq. in. abs., equivalent to 26:8 b.h.p. and a 
thermal efficiency (of the absorber alone) of 29-5 per 
cent. 
The orientation of these reflectors was east and 
west, and they did not ‘follow the sun,’’ consequently 
the output of steam fell off considerably in the morn- 
ing and evening. The solar radiation was received on 
only one side of the 1911 boiler, while the other side 
lost some of it, but, due to Prof. C. V. Boys, 
F.R.S., the boiler which the author tested in Egypt in 
1913 received heat on both of its sides, and its top 
edge as well, and the concentration was 4-6 to I. 
The orientation of the reflectors was north and south, 
and they were made automatically to ‘‘follow the 
sun.” Each reflector was trough-shaped, parabolic 
in cross section, 13 ft. 5 in. across the top and 205 ft. 
long, and there were five such sections. Hence 
13,752 Sq. ft. of solar radiation were collected. The 

