The British Government, viewing with concern the rising price of gasoline, last November appointed a committee to inquire into the production and utilization of alcohol as a motor fuel. This committee has recently submitted its report. It found that while alcohol is obtainable from molasses, potatoes, wood pulp and other vegetable products, the yield, contrary to popular opinion, is not large; that from potatoes, for instance, being only twenty gallons per ton. It can also be produced synthetically from coal and coke-oven gas, but the most promising source appears to be from tropical plants of which the sun-dried flowers of the mahua tree will yield ninety gallons per ton.

The usability of alcohol in internal-combustion engines with a properly designed carburetor and slightly modified compression is well recognized, so that there is no obstacle from the engineering standpoint. It is purely a commercial problem. Owing to the somewhat lower heat value of alcohol a correspondingly greater quantity must be used per horsepower-hour, so that in order to compete with gasoline the cost per gallon must be proportionately less.

As a means of keeping down the cost the committee recommends that the British Government modify the restrictions concerning the storage and distribution of alcohol, consistent with the prevention of its improper use-a recommendation that might well be given serious consideration in this country. It reports further that, while not definitely committed to the idea that the time has arrived when alcohol can compete commercially with gasoline, it believes nevertheless that such time is not far distant and strongly urges that steps be taken by the British Government to carry on such investigations and give such support to the alcohol industry as will put it on its feet to meet any further increase in the price of gasoline.

While true that the motor-fuel situation is much more acute in England than in this country, yet would it not be well for this government to profit by the recommendations of the British committee and by a little forethought through investigation avert a possible crisis a few years hence?

Some eight or ten years ago an effort was made to interest the farmer in the utilization of farm refuse for the production of alcohol on a small scale. To this end certain restrictions were removed, as applied to farms only, and the Department of Agriculture issued instruction pamphlets. The response to this effort, however, was small, perhaps owing to the then low price of gasoline and to the fact that the farmer at that time was not a large user of internal-combustion engines. But that condition has changed, the farmers now have their automobiles and are large users of internal-combustion engines to drive the various farming implements. Perhaps a renewal of the former efforts would now bring results.Power, 8/5.

DEVELOPMENT OF THE SEARCHLIGHT.-A review of the work of the Army Engineer Corps in the war, first issued by the War Department, says that the corps produced a new form of searchlight more powerful than any that had preceded it in any army, with which the Second Field Army had been partially equipped. "It weighed," the report says, one-eighth as much as lamps of former design, cost only one-third as much, was about one-fourth as large in bulk, and threw a light 10 per cent stronger than any other portable projector in existence." Still further to perfect the searchlight, our engineers were at work on a remote control when hostilities ceased.-Scientific American, 7/19.

BURNING POWDERED COAL.-With the increasing cost of coal, while at the same time the quality steadily decreases, it becomes of greater and greater importance to find the most efficient methods for combustion. The burning of coal in powdered form is conceded to-day by engineers to be the eventual method for coal combustion, since it offers opportunities for high

efficiency and controlled combustion not offered by any other method of burning.

Few people realize, unless closely in touch with this development, how much has been accomplished during the past five years. Since the early '90's the cement industry has been using powdered coal as its fuel, and to-day it may be said in all truth that the successful and cheap production of cement rests on the firing of rotary kilns with powdered coal as standard practice. In 1912-13-14, the use of powdered coal in firing numerous large reverberatory furnaces used for smelting copper ores was successfully worked out. To-day some of the great copper producers are burning hundreds of tons of powdered coal daily.

The use of powdered coal has reduced fuel consumption to such an extent that to-day some plants are smelting six tons of ore with only one ton of powdered coal. The whole trend of the copper smelting industry has been changed by the use of powdered coal in their enormous furnaces. In the early days powdered coal was injected into the furnace with a stream of high-pressure air. Even when firing in such a crude way as this, the results were such as to make the use of this fuel in the cement industry a much more efficient method of kiln firing than any other method used up to that time.

In developing the use of powdered coal in other fields where smaller furnaces were to be fired and more delicate operations carried on, it became necessary to work out other burning equipment in order to have better control over combustion, to speed up combustion and to get away from the disadvantages of injecting the coal stream with a jet of highpressure air and the poor mixture obtained by this method. This change to the use of low-pressure air was a change necessary to bring about the widespread application of this fuel as has been seen in the past five years. Equipment has been developed which is self-contained and easily regulated, and which will burn quantities of coal as low as one ounce per minute. From this extremely small capacity the equipment ranges up to the capacities demanded by the largest industrial furnaces and boilers.Engineering World, 7/15.

NEW CHISEL STEEL OF UNUSUAL PROPERTIES.-An American steel company, making all grades of electric tool steels, announces that it has produced an alloy chisel steel which can be made so hard that it will cut glass yet may be bent by being hammered over the edge of an anvil. This steel, the manufacturer states, has a wide temperature range, as it may be heated anywhere between 1650 and 1950 degrees F., and yet give good results.

The steel seems to have its greatest value when heated to 1750 to 1800 degrees, quenched in oil and slightly drawn. The drawing it is stated, does not seem to affect the hardness of the steel, but it helps the toughness. Many theories can be evolved as to just why this slight drawing is of such assistance to this steel, but metallographically there is no evidence of difference between straight hardening and hardening and drawing. The same structure can be produced as seen under the microscope, yet there is a great deal of difference between the two heat instruments.

A point emphasized is that the head of a chisel made of the new steel will not sliver. It is also stated that the head of the chisel can be heat treated so that it may be filed, yet it will not break out or crack. It will spread, but it will not split, yet the top of the head does not take on a very glassy surface and seems to have a grip on the hammer-face when it is struck.

It is pointed out that metallographically the steel is peculiar. It seems to have a very fine structure, which is difficult to define. It may be a solid solution which is generally regarded as austenite, or it may be martensite. It seems under the microscope to have an appearance at lower magnification of the whole range of solid solution steel, yet it has the characteristics of

none. Under high magnification of 1200 diameters the structure appears to be somewhat like martensite, yet the martensite appears to be lamellar rather than the usual 60 degrees marking.

The grain boundaries, which are particularly tenacious, have the coloring effect of troostite, yet they do not have the usual troostite formation. Troostite does not begin to form in round spots at the grain boundaries in Seminole steel, but seems to have the characteristic of broadening out the grain boundary into a dark line. From this stage the entire grain begins to etch a little more rapidly and take on a darker color, but the ground mass of the grain does not appear to alter in general characteristics as is usually found in the transformation from austenite, martensite, troostite and sorbite, as understood as applying to the usual form of alloy steels or carbon steels. Scientific American, 8/2.

COPPER IN RUSTPROOF STEEL.-In a paper recently read by D. M. Buck before the American Society for Testing Materials, it was brought out that very small amounts of copper have the effect of reducing corrosion in steel. Tests were made of open hearth steel with various copper additions, so that there was from 0.012 to 0.254 per cent of copper in the ingots. These were rolled into sheets and exposed to the atmosphere in the Connellsville coke region, together with a number of pieces in which there was no copper. It was found that a mere trace of copper was sufficient to prevent rapid corrosion.-Scientific American, 7/26.

SHIPPING BOARD TO MAKE DIESEL ENGINES.-According to recent dispatches from Washington, the United States Shipping Board has taken over the right to manufacture one of the standard European Diesel engines, and will manufacture them on a vast scale. This is in line with the decision of the Shipping Board made over a year ago to undertake motorship construction. Officials of the Board say that America is compelled to adopt the motorship to meet European competition.

Among the chief reasons for discarding the steamship in favor of the motorship are, according to the Shipping Board: Saving of two-thirds of the oil used as fuel. Saving of more than 25 per cent in wages due to the cutting down of the engine room force and the entire elimination of the fire-room gang. Increase of a vessel's steaming radius from a few thousand miles to not less than 30,000 miles. A contract for the construction of the engines has been let in Pennsylvania and in less than three months one completed Diesel engine will be delivered each day.-The Nautical Gazette, 7/19.

INTERESTING APPLICATION OF HEAT.-A recent issue of the General Electric Review describes a method of heat shrinking for fitting parts of electrical machines on to their shafts. The method overcomes various difficulties experienced with press fittings. Water or steam heating is used for flywheels and couplings, while for armatures and field systems conveniently situated heating resistances answer the requirements. In one case mentioned, i. e., a large armature, the shaft was 35 inches in diameter. Cold pressing would have required a maximum pressure of 600 tons. By heating the armature to about 80 degrees C., however, the shaft could be pulled on with a five-ton chain hoist.-Scientific American, 8/2.

LIBERTY. A TRADE-MARK Registered by the UNITED STATES OF AMERICA. -A certificate of registration of the trade-mark "Liberty as used on aeroplane engines was granted by the United States Patent Office to the United States of America on June 17, 1919. This is the first instance of the government of the United States registering a trade-mark under its own trade-mark laws, or the laws of any other country, although other governments have registered their marks in the United States Patent Office for the goods on which they are used. The Republic of France has registered

marks used on cigarettes, and several registrations have been granted by the United States Patent Office to the Imperial Government of Japan. Some government activities, such as the War and Navy Department's Commission on Training Camp Activities, have been granted registration of their trademarks.

Everything connected with the history of the mark "Liberty" as used by the United States on its aeroplane engines is unique. When the Liberty engine was first developed in the summer of 1917 it was referred to by the government engineers as the "United States Standard Aircraft Engine" or the "United States Standard Engine." Some genius, however, selected the right word and all the district offices of the Bureau of Aircraft Production, which was then the Equipment Division of the Signal Corps, were soon notified that the use of the word "Liberty" as applied to the new engine was so popular that it seemed inadvisable to attempt to use any other name. This word was a happy selection.

Trouble resulted in a short time, however, from the great popularity of the word "Liberty" as applied to articles of commerce. Many manufacturers began to designate their goods by the term "Liberty." This use of the term on goods which are of the same general class as engines or on goods adapted to be used on engines resulted in confusion and probably in deception. Government officials soon saw that it was necessary to protect the name. After considering several ways of getting the best protection of the right of the government in the use of the word "Liberty," the plan of registering it in the United States Patent Office under the United States Trade-mark Law was adopted. These proceedings resulted in the grant of certificate of registration No. 125,853, which under Section 16 of the Trademark Act constitutes prima facie evidence of ownership of the mark Liberty" as used on engines and parts thereof.-Aerial Age, 7/27.

TRANSLATING DRAWINGS FROM METRIC TO ENGLISH MEASUREMENT.Sometimes it is necessary to translate metric dimension drawings into fractional inch drawings, or vice versa. Incidentally different standards for pipes, bolts, threads, etc., are incorporated so that ultimately the two designs are not interchangeable.

If we establish the arbitrary rule that one inch shall equal 24 mm., all sixteenths may be expressed in millimeters and only one decimal place is involved. Now, 4 inches101.6 mm., while we made 4 inches 96 mm.; accordingly the metric version of the designer's pipe-dream has shrunk 42 per cent. This is generally quite harmless, but is eminently useful as it eliminates a great deal of figuring.

Gears of which the center distances have been translated in the above fashion will work out with metric (module) cutter with very little trouble. Take, for instance, two gears of 4 pitch with 14 and 19 teeth; the first has a pitch diameter of 31⁄2 inches and the latter 434 inches and the center distance is 4% inches.

According to our way of calculating 4% inches=99 mm. To get the module we divide, 2 X 99, by the sum of the teeth, thus:

The metric gears will thus figure out to be 6 X 1484 mm., and 6 × 19= 114 mm., and the center distance

According to the American Machinists Handbook the table comparing the pitch and module cutters or gears shows that the translated gear is just as strong-for all practical purposes-as the original gear. This example is not specially selected; it was chosen at random, but with

7-pitch gears, results may not be obtained at the first shot. This scheme is also friendly to metric bolt sizes as they increase by 3 mm. To proceed in the reverse direction two rules may be selected from. The first, 25 mm. I inch, gives all even millimeters in two decimals; the design shrinks less than 1 per cent, but involves the use of unwieldy decimals.

The second, 24 mm. I inch, gives all millimeters which are multiples of 11⁄2-inch sixteenths and the design swells about 5 per cent; for instance, 419 mm. is not a multiple of 1.5, the figure nearest to it is 418.5 171 inches and the error introduced if the latter figure is taken is perhaps not sufficient to throw the design out of plumb.

Needless to say, the above method of calculating, which is used by Dr. C. P. Schwartz, in the American Machinist, applies best when a design has to be adapted without attempt at interchangeability.-Engineering and Industrial Management, 7/10.

CONDENSERS ON TURBINE SHIPS PLYING IN THE TROPICS.-On a turbinepropelled vessel built to run between home and tropical countries it is essential that an ample condensing plant be installed to deal with the hightemperature sea-water of the tropics. Otherwise a considerable falling off in efficiency will take place, with a corresponding reduction in the speed of the vessel.

The adverse effect of high-temperature water on the vacuum in a condenser is very marked. Investigations and experience have shown that if provision be made for home waters only, a drop in vacuum of 11⁄2 inches to 2 inches may be expected in tropical waters. The reduction in economy and power developed with this reduced vacuum is appreciable, and may be taken at a minimum figure of 10 per cent, which would correspond to a reduction in the speed of a vessel of at least 3 per cent, or half a knot in a vessel of 17 knots normal speed.

The maximum temperature of sea-water in the tropics may be taken at 85° to 87° Fahr., and it is impossible under this condition, if the plant be properly designed, to obtain a vacuum of 271⁄2 inches. This entails a considerable increase in condensing surface over that required for home waters only, and may amount to at least 40 per cent of extra surface, with additional pumping capacity of probably half this amount.

The attainment of high vacuum with turbine machinery under all conditions of service is most important and the saving in economy effected by fitting an ample condensing plant will justify the extra cost involved in its manufacture.-Nautical Gazette, 7/19.

AERONAUTICS

HELIUM.-Up to the present time all military and most other balloons have been filled with hydrogen. This gas, although giving the greatest lift which it is possible to secure, is so highly inflammable as to make the destruction of balloons by fire, not only in war time, but during operations under ordinary conditions, a serious matter. For example, the writer happens to know personally of twenty-six cases in which kite balloons or dirigibles have been completely destroyed by fire, caused by atmospheric or frictional electricity, during the last two years. Many attempts have been made to minimize this fire hazard by fire-proofing balloon fabrics, and by use of hot air or ammonia in place of hydrogen, but so far without success. The use of helium instead of hydrogen affords absolute safety from fire, whether caused by accidental electric sparks or by incendiary or explosive bullets of an enemy in time of war. An adequate supply of helium will, therefore, entirely revolutionize balloon practices, and will do more than any other one thing to assure to the nation possessing it, that control of the air which will in the future be absolutely necessary for any adequate plan of national defence.