The Washington times., 1901-09-17
WITH THE SCIENTISTS.

"S fiobiSH Oi utltlLinS tHt sun . eH-
ergy is the subject of an article by Prof
Thurston in Casters Magazine" for Au-
gust. He points out that in spite of the
enormous deposits of coal remaining I'M
touched in other sections OF the globe
within few generations at most. some
other energy than that of combustion OF
fossil fuel must be relied upon to do the
work of the civilized world. He speaks
of the next important source of energy
water power-and shows that the energy
capable of use in the area drained by the
Mississippi River, for instance, may be
taken at about 250.0c0 horse power per
square mile, but that such figures are OF
little value, as the available water power
must be calculated from the minimum
volume under easily utilizable heads, the
six inches per mile fall of the Missis-
sippi-with the exception of the three
small notwithstanding of no use what
ever. Prof. Thurston disposes of wind
power and tidal power in a few words.
and then devotes his article to the con-
sideration of the possibility of converting
the heat of the sun into mechanical en-
ergy by some direct means.
He refers to John Ericsson's contribu-
tions to the Centennial Exhibition in 1876.
and the figures quoted are interesting. 1t
would appear that with Mr.. Ericssons
concentration apparatus, during nine
hours per day. an average of fully 3.5
units of heat per minute can be extracted
for each square foot of area presented
perpendicularly to the suns rays in all
latitudes between the equator and As de-
grees of latitude. Theoretically, this works
out to So horse power for an area of 1O0
feet. 1t appears that there is rainless
region extending from the northwest
coast of Africa to Mongolia, 5000 miles
in length. and nearly 1000 miles wide. Be-
sides the North African deserts, this
region includes the southern coast of the
Mediterranean. east of the Gulf of Cabes.
Upper Egypt, eastern and part of the
western coast of the Red Sea, part of
Syria. the eastern part of the countries
watered by the Euphrates aud Tigris,
Eastern Arabia, the greater part of
Persia, the extreme yestern part of China,
and lastly, Mongolia. In the Western
Hemisphere, Lower California. the table
land of Mexico and Guatemala. and the
west coast of South America, suffer from
continuous intense radiant heat for dis
tance of more than 2.000 miles.
Calculations based upon the assumption
that one horse power could be developed
for every 100 square feet exposed to solar
radiation would lead one to enormous
figures II applied to the area above men,
toned. For the purpose of example. how
ever, Mr.. Ericsson takes strip of land
a single mile in width, along the rainless
western coast OF America, the southern
coast of the Mediterranean. both sides of
the alluvial plain of the Nile In Upper
Egypt, both sides of the Euphrates and
Tigris for a distance of 400 miles above
the Persian Gulf, and finally a strip also
a mile wide along the rainless portions
of the Red Sea above alluded to. The
aggregate length of these strips of land.
selected on account of their being acces-
sible by water. far exceeds 5000 miles.
The area covered would be about 223.ooo,-
600 square feet, and on the assumption
that 100 square feet could produce one
horse power during an average of nine
hours per day we are led to the conclu-
sion that by suitable apparatus 22,300,0oo
engines, each of 100 horse power. could
be kept working by utilizing only that
heat which is now wasted on the assum-
ed small fraction of similar land extend
ing along some of the water fronts of
the sunburned regions of the earth.
According to Prof. Thurston, this fig
ure has been confirmed by recent expert
ments at Pasadena, in California, where
1t was stated that Ericsson's efficiency
has In some cases been attained. Tne ap-
paratus used In California was truncat-
ed conical mirror, 80 feet inches in
diameter at the top and Is feet at the bot
tom, which concentrates the rays of the
sun received upon its 1,1SS facets at
focus, where a boiler is placed and steam
generated to work steam engine. The
whole mass is moved by clockwork and
held with its axis directed
toward the sun. The boiler, which il
with the mirror, is l3 feet inches in
length, and contains about 10 cubic feet
of water and cubic feet of steam space,
pressure being maintained at $50 pounds
per square inch. The apparatus is said to
be OF ten horse power. but Prof. Thurston
that the reported figures are in
with this rating.
According to the report of the British
Consul General at Marseilles. artificial in
iigo is killing the natural product on the
French market. the artificial product al
ready regulating prices. The Badische
Company have for two years been max
Ing indigo near Lyons for local consump-
tion, while the Hochster Farbwerke are
synthetic indigo by an
other process in the same city. Artificial
indigo is classed for customs duty with
indigo, and since goods dyed with
Il are not required to be declared as SUCH
tney are SOiu AT similar prices TO goods
dyed with natural indigo. Lyons dyers of
cotton and woolen goods and Lyons dealers
IN indigo say that natural indigo has been
busted from many dye works. especially
since artificial indigo has been prepared
by crushing. Small dyers favor synthetic
indigo. because they can buy small guam
titles as required, and prices do not vio-
lently fluctuate. But. as the vegetable
dye gives more solidly to the cloth, II
IS still likely TO be used for military uni
forms. DIR. Calmette of Lille is said to
have patented process for extracting
ndigotin from vegetable indigo up TO
hrice the quantity produced by the more
primitive methods. 1t is curious that the
Bengal Chamber of Commerce have re-
,ently had to ask the Havre Chamber to
abolish rule under which indigo tend
cred in that important terminal market
must be guaranteed TO be manufactured
Dy the old process-a serious restric-
ion, in view of the many new processes
-ecenty introduced. The request has
leen complied with. and certificates will
rot be needed after April l next. From
he consular report on Frankfort-on-
Main for 1900 1t appears that the Badische
Company has borrowed 100000 marks
or the purpose of enlarging the produc-
ion of artificial indigo and reducing its
,ost
WHEN GRABBERS DISAGREE.