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Completes the Circuit between 
You and Progress 
q CLEAN, WHOLESOME, INSTRUCTIVE AND ENTERTAINING, THE 
Scientific American 
is unique in the current literature of the world and ranks among the great 
periodicals which are regarded as distinctly American Institutions. 
Its accurate, popularly written articles open to the intelligent mind 
the mysteries of science, mirror the inventive genius of the American 
same results are constantly being devised. In a word, the “SCIENTIFIC 
AMERICAN” is a source of inspiration and entertainment to every 
intelligent reader. 
DURING THE YEAR 1910 
there will be found in the weekly issues of the ‘“ SCIENTIFIC 
AMERICAN” illustrated articles on the leading events of the day in 
regard to Aeronautics, Automobiles, the Navy, Engineering Works, 
Scientific News, etc. Our brief notes on Electricity, Engineering and 
Science are published in each issue. Our Correspondence Column 
contains letters from all parts of the world. Inour Notes and Queries 
Department are published replies to correspondents in regard to the 
widest range of topics, and an able corps of experts is engaged to 
attend to these queries. A complete list of all patents issued in the 
United States appears in each issue. A department entitled the 
“Handy Man’s Workshop” is published every second or third week. 
We have special correspondents in the various capitals of Europe. 
The “SCIENTIFIC AMERICAN ”’ is, in fact, a Newspaper 
of Progress, and as such no intelligent family can afford to be 
without it. Subscription price, $3.00 per year. 
Read the “SCIENTIFIC AMERICAN” for Two Months Free 
With a view of extending our subscription list we are prepared for a limited period to 
make you the following: 
SPECIAL OFFER 
If you will fill out the attached coupon and mail it to us with a remittance of $3.00 
in payment for a New subscription for “SCIENTIFIC AMERICAN ” we will enter 
the subscription for one year commencing January 1, 1910, and we will also send 
you absolutely free the numbers for November and December, 1909. 
COUPON 
MUNN & CO., Inc. 
You will thus receive the “SCIENTIFIC AMERICAN” FOR FOURTEEN & Enclosed please 
MONTHS for the price of one year’s subscription. To those who act quickly > find $3.00 for which 
we will also send in addition to the above a copy of our Special Hudson- < send me “Scientific 
Fulton” Souvenir number. This magnificent number has thirty-two American” for one 
pages brimful of timely information and illustrations regarding the my year from Jan. 1,1910 
great explorer and the famous engineer, giving a history of the evolu- KY with Nov. and Dec.. 1909. 
tion of the River Steamboat in the United States and other topics of 
interest. 
As the number of copies of this “Grand Souvenir” available 
for this purpose is very limited it will be necessary for you to 
send in your order at once in order to secure a copy. 
MUNN @® CO., Inc. 
365 BROADWAY NEW YORK, N. Y. 
numbers and a copy of 
Special “Hudson - Fulton” 
Souvenir number free as per 
special offer. 
Name 
The Scientific American Boy 
By A. RUSSELL BOND 
12mo. 320 Pages. 340 Illustrations. Price, $2.00, Postpaid. 
i is a story of outdoor boy life, suggesting a large num- 
ber of diversions which, aside from affording entertainment, 
will stimulate in boys the creative spirit. In each instance 
complete practical instructions are given for building the various 
articles. @ The needs of the boy camper are supplied by the direc- 
tions for making tramping outfits, sleeping bags and tents; also 
such other shelters as tree houses, straw huts, log cabins and caves. 
q The winter diversions include instructions for making six kinds of 
skate sails and eight kinds of snowshoes and skis, besides ice boats, 
scooters, sledges, toboggans and a peculiar Swedish contrivance 
called a ‘‘rennwolf.” @ Among the more instructive subjects cov- 
ered are surveying, wigwagging, heliographing and bridge-building, 
in which six different kinds of bridges, including a simple can- 
tilever bridge, are described. 
FOR SALE AT ALL BOOKSTORES 
Workman, show how dreams have become realities and that however \ 
well things have been done heretofore, better means of accomplishing the : 
November, 1909 
Between thirty and forty towns are lighted 
on this plan in Europe. In England there are 
about six thousand installations, which include 
hundreds of public buildings, railway stations, 
etc. About twenty or thirty plants are in- 
stalled in India. 
SOAPS FOR REMOVING SPOTS 
Mee soaps sold as spot-removers are 
ordinary cocoanut-oil soaps, and re- 
move only the spots which are pre- 
pared for the purpose by the vender. For ex- 
ample, spots made by daubing cotton goods 
with a mixture of tar and acid can be removed 
with pure water, and completely disappear 
when washed with ordinary soap. ‘True spot- 
removing soaps contain oxgall and turpentine, 
which can be detected by their characteristic 
and powerful odors, even if the soaps are 
scented. 
A good spot-removing soap may be made by 
mixing 20 parts by weight of good hard white 
soap, in very small pieces, with 8 parts of 
water and 12 parts of oxgall. “The mixture is 
allowed to stand over night and is then heated 
gently until solution is complete. The heating 
is continued a little longer, in order to evapo- 
rate some of the water, and 1% part of oil of 
turpentine and 1% part of benzine are stirred 
in, after the vessel has been removed from the 
fire. ‘The still liquid soap is then colored with 
a little ultramarine green, dissolved in ammo- 
nia, and is poured into molds, which are at 
once covered. 
The following process is also recommended, 
but it requires some care, as the soap is easily 
separated by agitation, especially if the oxgall 
is not fresh. In a vessel heated on a water 
bath, 28 parts by weight of cocoanut oil are 
thoroughly incorporated with 5 parts of talc 
or fuller’s earth, 1/10 part of brilliant green 
and 1/50 part of ultramarine green. The 
mixture is allowed to cool to 90 deg. F.; 14 
parts by weight of lye of a strength of 38 
Baumé are then added and, after saponification 
is completed, 5 parts of oxgall are stirred in. 
If any separation takes place, the vessel is 
closely covered and heated on the water bath 
until the mixture becomes uniform. Finally, 
WY part of turpentine and about 8 parts of ben- 
zine are added and the soap is poured into 
molds. 
COMBATING INJURIOUS INSECTS 
WITH THE AID OF THEIR 
NATURAL ENEMIES 
N INTERESTING instance of success- 
A ful warfare waged against injurious 
insects with the aid of their natural 
enemies is reported from Hawaii, where the 
sugar plantations have in recent years been 
threatened with annihilation by the ravages 
of a small cicada, little more than one- 
eighth of an inch long. Professor Kirkaldy, 
the director of the Honolulu Entomological 
Station, has described the little insect and 
named it Parkinstiella saccharicida. It pierces 
the stem of the sugar-cane and extracts the 
sap, causing the plant to wither and die. 
The formidable character of this insect pest 
is due to the amazing rapidity with which 
it multiplies. Six generations are produced 
annually and, on assumption that 20 females 
of each brood live to reproduce their kind, 
it is estimated that the progeny of one 
female, produced in the course of a single year, 
numbers 64,000,000. ‘The insect was un- 
doubtedly introduced with the sugar-cane from 
other countries into Hawaii, where it has 
multiplied enormously, as its natural enemies, 
which limit its numbers elsewhere, do not 
appear to have been imported with it. Ento- 
mologists were, therefore, sent abroad to dis- 
cover the original home of the little cicada, 
to find its natural enemies, and to bring these 
