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Lifting Magnets

Will you be kind enough to give me a sketch and explanation of the lifting magnets used in machine shops?—T. H. W.

The accompanying sketches, Figures 1 and 2, represent two different forms of lifting magnets which are in common use at the present time. The views show a cross section. In Figure 1 two coils are wound about the ends of an iron bar, B, this bar being bent into the shape of a horse shoe. By sending a current through the coils AA, the iron becomes magnetized and will attract any magnetic substance such as iron or steel. Figure 2 shows a magnet of a different type. There is one coil, A, which is wound in a circular form. Both drawings will explain themselves.

Electric Limit Switches

What are electric limit switches?—D. J. M.

It was found in operating electric elevators that more space was needed between the cab and the overhead sheaves at the upper end of the run, and that a deeper pit was also required at the bottom of the run, on account of the occasional slip of the brake. For, frequently, although the mechanical, automatic or limit stop on the machine would break the circuit and apply the brake near the end of the trip, there were cases—

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when the empty cage was required to ascend at full speed and the brake had become slightly worn and did not grip as firmly as usual—that the cage would go beyond the landing, and the additional space mentioned above was required to prevent a collision. This also happened sometimes at the lower end of the run when an extra heavy load was descending. A lack of care on the part of the operator in breaking the circuit in sufficient time, or the causes just mentioned, would cause the cage to run down to the bottom and bump. To avoid this, as an extra measure of safety, switches are sometimes placed at the extreme limit of the run, the line wire being carried up the hatchway through the switch and returned. These switches are opened by the car automatically if it should pass a certain point, and the opening of this switch breaks the circuit and at the same time supplies an extra strong emergency brake.

Wheat Bin that Won't Leak

Could you tell mc how to build a non-leakable wheat bin ?—H M. T.

The diagram herewith shown is an end view of the bin. The dimensions and structure can be seen at a glance. The hopper should first be built. Next put in the rafters, floor them, being sure to run the flooring crosswise and running out past where the studding will be. The studding should be cut on a bevel to fit the hopper. *

To Color Electric Light Bulbs

Please print directions for coloring electric light bulbs.—F. R. S.

Beat the white of one egg to a froth and mix with one pint of soft water. Strain through a fine sieve, being very careful that no bubbles remain on the surface of the liquid. Clean and polish the bulb, and hang to dry. Half an hour later again dip the bulb and let dry. Now dissolve ten to thirty grains of powdered dye, according to the degree of shading desired, in four ounces of collodion. Plunge the bulbs therein and dry as before.

To Produce Aluminum

Can aluminum be produced by any other means than electrolysis ?—G. D. F.

Electrolysis is the only practical method known for manufacturing aluminum. All attempts to make aluminum in the electric furnace by reduction of aluminum with carbon have proved unsuccessful. The product thus obtained is almost exclusively aluminum carbide.

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To Make Pencil Sharpener

How can I make a simple pencil point sharpener?—B. K.

Take a paper dip, A, and a piece of

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emery cloth, B. Fold the edges over as shown. The pencil point is placed in the crevice and moved up and down, resulting in a point as fine as may be desired. If the pencil is revolved between the fingers while sharpening a round point will be the result.

Tests for Boiler Water

Will you please print some simple tests for boiler water?—E. G. A.

Test for hard or soft water: Dissolve a small piece of good soap in alcohol. Let a few drops of the solution fall into a glass of the water. If it turns milky, it is hard water; if it turns clear, it is soft water.

Test for earthy matters or alkali: Take litmus-paper dipped in vinegar, and, if on immersion the paper returns to its true shade, the water does not contain earthy matter or alkali. If a few drops of syrup be added to a water containing any earthy matter, it will turn green.

Test for carbonic acid: Take equal parts of water and clear lime water. If combined or free carbonic acid is present, a precipitate is seen, and if a few drops of muriatic acid be added, effervesence commences.

Test of magnesia: Boil the water to twentieth part of its weight, and then drop a few grains of neutral carbonate of ammonia into a glass of it and a few drops of phosphate of soda. If magnesia is present, it will fall to the bottom.

Test for iron: Boil a little nut-gall and add to the water. If it turns gray or slate-black, iron is present. Second': Dissolve a little prussiate of potash, and, if iron is present, it will turn blue.

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Modern Plumbing Illustrated. By R. M.

Starbuck. Cloth. 392 pp. 55 Full page detailed plates with index. 1907. 7% In. by 104 In. The Norman W. Henley Publishing Co., New York. Price

94.00.

In the author's preface it is stated that there is, perhaps, no branch of construction work which has undergone within the same given time changes of a nature so far-reaching as in plumbing construction.

As the work covers almost the entire field of plumbing, and is written in a clear and concise manner, illustrated with detailed drawings it should be especially useful to the young men of the profession. The old-timers can also find much to interest them in description of new methods of construction and use of cesspools, automatic control of hot-water tanks, flushing, etc., and suggestions for estimating.

The practical hints so well illustrated with the carefully made drawings are of incalculable value to the up-to-date plumber, as well as to owners of buildings who should know personally that no old-fashioned methods are used in their ^plumbing construction.

Modern Milling: Machines. By Joseph a.

Horner. Cloth. 3o4 pp. 269 illustrations with index. 1906. 6 In. by 9 In. The Norman W. Henley Publishing Co., of New York. Price $4.00.

The book is devoted entirely to the one department of machine shop practice, the milling machine, and the author handles the subject well, giving the history of its development, and going into all the details of the construction and operation of the earliest makes down to those oi the present day.

The typical methods of holding work, as well as some fixtures and jigs will serve as excellent guides to machineattendants and the chapter on feeds and speeds will clear up many difficulties for them.

We recommend this book, as about the most comprehensive published, to every practical shopman who expects to keep well posted on the latest phases of milling machine work.

Engineering Materials. By

Marks. Cloth. 98 pp. 38 Illustrations with Indec. 1906. 5 in. bv 74 in. New and enlarged edition. Tbe Technical Publishing Co. Ltd. London. Price 2s. 6d.

Of the many excellent treatises on metallurgy and mechanical engineering this little book varies from the beaten path of dealing exhaustively with the extraction and preparation of metals and alloys, machines and structures, and gives in handy form practical information to assist those using engineering materials to make a selection. The short chapter on Metals for Bearings is alone well worth the price of the book.

Boiler Waters. By William Wallace Christie. Cloth. 235 pp. 71 Illustrations with index. i9o6. 6 In. by 9 in. D. Van Nostrand Co., New York. Price $3.00.

Steam users in general will find the information on water contained in this book very helpful, especially in overcoming troubles arising from the use of water. Next to the boiler itself, the water to be used is the most important consideration in a steam plant.

The long chapters on corrosion and water-softening in addition to the chemical explanations give practical descriptions and suggestions in a popular way easily understood by the ordinary engineer.

So much trouble has been and is caused by boiler water, we think the author has made no mistake in giving up this entire volume to the subject. Of his many works we think this the best, and feel sure it will be the cause of removing much of the engineer's trouble, as well as decrease operating expenses.

Brooke's Twentieth Century Machine

Shop Practice. By L. Elliot Brookes. Cloth. 661 pp. 423 Illustrations with Index. 19o6. 5', in. by 754 In. Frederick J. Drake & Co., Publisher, Chicago.

This book contains a large number of useful rules, formulas and tables valuable to Machinists, Engineers and others interested in the use and operation of the Machinery and Machine Tools of a modern machine shop.

Such subjects as Arithmetic, Mensuration, Applied Mechanics, Measuring Devices, Shop Tools and Machine Tools, are treated in a very practical and nontechnical manner. The chapter on Shop Kinks is a feature to be especially commended.

SeeKing' Trichinae in PorR

By FranRlira Hortoini

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springs of watches. The wages the government pays the young women vary according to their proficiency, some earning twenty dollars a week.

The new government regulations say the microscopic examination of pork shall be as follows: "The inspector in charge, or his assistant, shall take from each carcass a sample consisting of three specimens—one from the pillar of the diaphragm, one from the psoas muscle, and one from the inner aspect of the shoulder. These shall be placed in a small tin box and a numbered tag placed on the carcass from which they were taken, a duplicate of said tag being placed in the sample box. The boxes shall then be taken to the microscopist, who shall thereupon cause to be made a microscopic examination of each sample and shall furnish a written report, giving the numbers of all samples affected with trichinae."

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Carcasses affected with trichinae are disposed of according to law. Those which have passed the test are kept in separate cellars "where no other meats shall be cured, stored, packed, or labeled." Keys to these cellars remain in the possession of the government inspectors, and are handed to employes when necessary.

"The greatest diligence." says the department of agriculture regulation,

"shall be exercised in the handling of sausage, brawn, and other products of a similar nature that are prepared from microscopically inspected meats. Such sausage shall be kept in separate locked compartments, prepared in separate rooms, and chopped in choppers used only for such sausage. Each ham and other cut shall be marked with a seal denoting microscopic inspection."

This microscopic examination is costly, the last government report showing 9,020.521 pounds were examined in the year, at an expense of $53.934—an average of 17 1-10 cents for each carcass examined, or three-fifths of a cent for each pound of pork exported, but in the interest of health is necessary.

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The Hill

I am home-sick for a hill,
For a barren hill and bare.
I have dreamed of it through days
Of the blinding city glare,
When my tired-lidded eyes
Ached for something far to see,
I have dreamed of how it stood,
And how cool its shade must be.

Now I know the north winds come,
Meet the winds from out the west,
And upon its barren slope
In gigantic battle wrest.
From the city let me go
On its heathered face to lie,
That the winds may sweep my soul
Clear as they have swept the sky.

Lucy Copinger, in LiHincott's.

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