NATURE 
[APRIL 4, 1912 
THE SHUMAN SUN-HEAT ABSORBER. 
OST of the experimenters who have aitempted 
to make direct use of the sun’s heat for the 
production of power have adopted the practice of 
greatly concentrating the sun’s rays and focussing 
them on to a comparatively small and strong boiler 
Fic. 1.—Showing one section of absorber on left, steam main and safety valve in centre, and part of engine on right 
generating steam at a fairly high pressure. Mr. 
Frank Shuman has used a concentration of only two 
to one, though in the next plant, which will be mate- 
rially different (due to certain recommendations of 
Prof. C. V. Boys, F.R.S.) from the one herein 
referred to, the concentration will be three to one. 
The boilers are lamellar, about a 
yard square, and only about one- 
quarter inch thick. They are made 
of thin tinned copper, painted dull 
black on the outside, with a 
number of opposed indentations, 
the tinning holding the two 
sheets together where these inden- 
tations touch. 
The boilers are fixed in shallow 
boxes placed nearly horizontally, 
and having double glass tops with 
an air space of one inch between the 
two sheets of glass. Between the 
lower sheet of glass and the top of 
the boiler there is another air space 
of one inch, and below the boiler an 
air space of about half an inch; 
then a sheet of millboard one- 
quarter inch thick, then two inches 
of granulated cork, and, lastly, a 
second sheet of millboard three-eighths of an inch 
thick forming the bottom of the box. Each such unit 
is a yard square, but twenty-two of them are con- 
structed side by side in one frame, forming one sec- 
tion, and in the plant tested there were twenty-six 
such sections, thirteen on each side of the main steam 
NO. 2214, VOL. 89] 
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pipe. To the top edge of each unit a silvered glass 
mirror a yard square is attached making an 
angle of 120° with the glazing of the unit. 
To the bottom edge a similar mirror is simi- 
larly fixed. The top edges of the mirror are 
thus six feet apart, while the bottom edges ate three 
feet apart; hence the concentration of two to one. 
Along the  bot- 
5 ~ tom of each section 
there is a_ small 
pipe for supplying 
the feed water, 
while a larger pipe’ 
runs along the top 
edge to collect the 
steam and convey 
it to the eight-inch 
main steam pipe. 
Each section is 
supported by, and 
pivoted to, steel A 
frames, each with 
a notched quad- 
cant; “SO! vasi ante 
enable the section 
to be inclined at 
different angles. 
Herein is another 
distinct feature of 
the Shuman = sun- 
heat absorber. 
Practically all the 
absorbers using 
great concentration 
of the sun’s rays 
have had to be 
focussed — continu- 
ously on to the sun, 
but the absorber 
now being described 
needs _ adjusting 
only once about 
every three weeks, the adjustment being such that the 
rays at noon are perpendicular to the top surface of 
the boilers. 
When experimenting at Philadelphia in July, 1910, 
with a single unit and no mirrors, the maximum tem- 
perature I recorded under the lower cover glass was 
- nn 
Fic. 2.—View showing the whole of the absorber. 
250° F., and temperatures of over 200° F. were 
common. Even in the latter cases steam was formed 
freely, showing that the temperature of the boiler 
was 212° F, 
The absorber I tested in August, 1911, had a 
collecting area of 10,296 square feet, and, with the 
