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URREY, TYPE TWO has ample power for rough roads and hills; has throttle (speed regulator) attached to steering wheel-one hand can manage both; automatic spark governor; cooling system that makes pumps and fans unnecessary; powerful brakes long wheel base; large wheels and tires; can opy top; water-proof side curtains; plate-glass swinging front; and other marked provisions for comfort, safety and reliability. $2000, complete with lamps, tools, etc. Other models $750, $850 $1350, $3000 THOMAS B. JEFFERY & COMPANY Main Office and Factory, Kenosha, Wisconsin Branches, Boston, Chicago, Philadelphia New York Agency, 134 West Thirty-eighth Street Representatives in all other leading cities.

Mention The Technical World.

For Experts

Engineers, Architects, Draughtsmen-Students or Expertsshould get acquainted with the resources of supply for all drawing and sketching materials offered by this house.

Our catalogue contains the facts and the figures about it all. Our goods contain the quality that real experts appreciate. We send the book to anybody who is interested in the goods.

Devoe & Raynolds Company

176 Randolph Street, Chicago
Fulton and William Sts., New York
1214 Grand Ave., Kansas City, Mo.


Averages 700 Pages with 700 Illustrations

of the most practical and instructive articles, regarding the designing, building and operating of motor-driven vessels, that can be written-; price $2.00 a year domestic 2.50 a year foreign Sample copy free


17 Battery Place.. New York, U. S. A.

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Answer: The voltage of a battery does not always indicate the state of charge. One method of finding the amount of charge in a storage battery is called the "Cadmium Test." The apparatus for making this test may consist of a small piece of cadmium, 5% inch by 5% inch by 1-32 inch, mounted so that a glass tube contains the conducting wire, wax being used to protect the soldered joint of copper and cadmium. With normal conditions of cell when fully charged and on open circuit, the difference of potential between the cadmium piece and the positive plate is approximately 2.5 volts, which is sufficient. The cadmium test is usually made at the center of the cell, giving uniform current distribution. The test will give readings, some of which are below 2.5 volts, if hydrometer test, temperature, and charge data show that the cell is not fully charged; but if the hydrometer, temperature, and other data show the charge to be complete, and the cadmium gives .I volt or more below 2.5 volts, the defective plate is determined by individual cadmium readings. When the battery is discharged—that is,


Mention The Technical World.

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Main Building, Armour Institute of Technology

Preparation for College


Instruction under the direction of the regular teachers in a resident engineering college.

Lessons prepared especially for home study by teachers of acknowledged standing.

The full College Preparatory Course covers the entrance requirements of such a college as ARMOUR INSTITUTE OF TECHNOLOGY, and students satisfactorily completing this course are admitted to the college of engineering of that institution without further examination in the subjects taken.

An unusual opportunity for young men of limited means to prepare for entrance to an engineering college without leaving home or interfering with their regular work.

PARENTS wishing to KEEP THEIR CHILDREN AT HOME as long as possible before sending them to college will find these courses of great value. There is no breaking of home ties, and the student not only has many of the advantages of a private tutor but also the sympathy and encouragement of his parents.

This is an excellent opportunity for teachers and others to take up engineering studies in their own homes and at their own convenience under the guidance of resident school teachers.

In addition to the College Preparatory Course instruction is also offered in

Hardening of Steel Tools

Question: Is it good practice to use acid baths for hardening steel tools? If not, what is a good formula?-E. S. K.

Answer: With acid baths, excellent results, so far as the hardened surface is concerned, can be obtained. Their use is not advocated, however, as the after effect is to rot the steel. A bath that gives excellent results is: Six quarts of soft water, one ounce of corrosive sublimate, and two handfuls of common table salt. Use when dissolved. Another formula for making tools tough and hard is: 1⁄2 teacupful salt, 1⁄2 ounce saltpeter, I teaspoonful pulverized alum, and I gallon Mention The Technical World, Feb. soft water. Mention The Technical World.

Mathematics (Arithmetic, Algebra, Geometry and Trigonometry), Electrical, Mechanical, Steam, Sanitary and Civil Engineering: Architecture, Mechanical Drawing, Telegraphy, Telephony and the manufacture of Textiles (Spinning, Weaving and Knitting).

200 page illustrated Bulletin, giving full information as to courses, teachers, methods of study, etc., may be had upon request.

American School of Correspondence


CONSULTING DEPARTMENT-(Continued) to 1.8 volts-the voltage between the cadmium test piece and the positive plate should be about 2.05; and between the cadmium and the negative plate, .25. The cadmium should be positive to both elements. The voltage of the cell equals 2.05 .25 (= 1.8). If we have a cell in which the conditions tend to show full charge but the potential difference is low, a cadmium test is made. Whichever plate shows a falling off from the normal reading, that plate is the defective one.

The following precautions should be taken in making this test: It is advisable to have the cadmium plate wet before the test is made. The cadmium plate should be shaken occasionally to free it from any bubbles of gas that may form on the surface. The plate should be washed with water every time it is taken from the cell. The simplest way to accomplish this is to keep the cadmium tester in a beaker of distilled water. The cadmium should be free from impurities or foreign matter of any kind.

Armour Institute of Technology


The surface of the metal should not be scraped bright, but it should be allowed to oxidize slightly. There is a difference of potential between cadmium and cadmium oxide; and, as the bright surface oxidizes quickly, it would be practically impossible to keep the surface bright. Care should be taken that the cadmium does not come in contact with plates or connections. This may be prevented by covering the cadmium with rubber, and perforating the covering with numerous small holes.


Copyright, 1904.

Patent Applied For.





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But a useful, practical, durable and convenient article for everyone. Fits nicely in vest pocket. Handy for Farmers to take to barn at night.-No danger of fire-can't blow out-always ready-simply press the button and you have instant light. Invaluable for PHYSICIANS, WATCHMEN, PLUMBERS, CLERGYMEN, MINERS, RAILROAD MEN, BANKERS, HUNTERS. TRAVELERS, ETC. Women folks find it handy about the house for cellar, dark corners, etc.-in fact, everywhere a bright, safe light is wanted. No heat, matches, chemicals. SAFE-a child can operate it. No wire, smoke, smell or dirt. Nothing to break-it lasts for years. New Batteries, 30e, Bulbs, 35e, each, postpaid. Can change instantly. Once you bave it, you would never be without it. Send today for free electrical catalog-it shows a large line of USEFUL electrical novelties for all purposes. AGENTS make big money selling our goods. Write for terms. Sutcliffe & Co., 518 S. Main St., Fall River, Mass.


RE you interested in
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Plants, complete, or parts
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If your Subscription Expires

with this issue or with the next, or if you are not a subscriber see the special announcement on pages VIII and IX in the front section of this issue. It will interest you.

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The basis of this new profession is Hygieneall that makes for health-personal hygiene, healthful surroundings, healthful food, cooking, clothing, care of the sick, the right care of children, etc. Then comes the Economy of Living-true economy of time, effort and expenditure, system of work, household conveniences, the division of income, buying, household accounting, etc. Then, the Simple Life-living in a simple, rational, artistic way; and-most important-the Children, whose health, character and final success in life is so largely determined by the home care and training.

Every woman who would like to have something better than tradition, hear-say, and scraps of information as guide in her life work will be interested in the Announcement of the American School of Household Economics which tells of the authoritative correspondence instruction and advice given by prominent teachers of the "profession of homemaking."

This attractive, illustrated 48-page book will be mailed free to any one sending a postcard addressed A. S. H. E. 3311 Armour Avenue, Chicago, Ill.

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