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The history of helium is interesting. About 70 years ago, a line was discovered in the spectrum of the sun's atmosphere, which could not be identified as belonging to any element known on the earth. This unknown gas was, therefore, named helium. Many years later, a thimble full of a gas, occurring in very minute quantities in the earth's atmosphere, was isolated by Sir William Ramsay, and proved to be the hitherto unknown element to which the name helium had been given. It was then proved to be not only incombustible, but inert in every other chemical way and to have about twice the density of hydrogen. Still later it appeared that this gas is formed whenever radium or any other radio active material disintegrates and for a time active chief source from which helium was obtained in small quantities for scientific research was certain radio active minerals. Still later helium was found to be a constituent of certain natural gases, particularly those occurring in Southern Kansas, parts of Oklahoma and Northern Texas, and processes were developed at the University of Kansas for purifying it so cheaply that it could be sold to scientists, in small quantities, at something like $1700.00 per cubic foot. At that time the total quantity of reasonably pure helium in the world was probably less than 100 cubic feet. In the face of so discouraging an outlook, some one in the British Admiralty had imagination enough to propose seriously that helium should be produced in sufficient quantities for the British Balloon Service, and experiments were undertaken in Canada for this purpose. A report on this matter was found in a mess of British documents sent to this country soon after we entered the war, by the Gas Warfare Committee of the Bureau of Mines and the matter was brought to the attention of the Signal Corps and the Bureau of Steam Engineering. Since that time about six millions have been either spent or obligated, the entire practicability of the production of helium on a large scale at a cost of ten to fifteen cents per cubic foot has been demonstrated, and production plants to yield 40,000 to 60,000 cubic feet per day are now being constructed or under test.

Three processes, alike in fundamental principles, but differing in important details, are being tried. One of these, the Linde process, has demonstrated its success and is the basis of the production plant now being built. The second, the Claude process, gives promise of a somewhat lower operating cost than the Linde process, but has not yet been entirely perfected. At present, this plant is temporarily shut down until the new government pipe-line can provide it with an adequate supply of undiluted Petrolia gas, at which time the final test will be made. The third process, invented by Norton and developed by the Bureau of Mines, is the basis of the large experimental unit in Plant No. 3. This unit is still being worked into shape by Norton, the inventor, and it is hoped that satisfactory results will be forthcoming within the next two months. It gives promise of an operating cost lower than either of the others.

The active supervision of the production program for helium, with the exception of Plant No. 3, has been placed in the hands of the Navy Department by mutual agreement between the army and navy. All that it is necessary for the army to do at the present time is, therefore, first, to keep in touch with the work the navy is doing in behalf of both departments; second, to prepare itself for the proper utilization of the helium that will be supplied to it under the agreement with the navy, and, third, to assume the responsibility of providing an adequate supply of the necessary raw material, in the future.

It is further suggested that there is much to be done before the army will be ready to use this new gas in the most effective way. A small repurification plant has already been authorized and plans for it are nearly completed. The question of modifying the designs of the various types of balloons in use, so as to make them appropriate for helium, should be undertaken at once. The chief difficulty is connected with the very large

waste of gas involved in the methods of handling balloons at present in use. This waste of gas will have to be very largely reduced by careful experimentation and by changes both in balloons and in the manual of tactics before the use of helium in balloons of the army types will be justified from the point of view of the whole problem of national defence.

Finally, it must be remembered that the supply of helium in the United States, although large, is by no means unlimited. At the present time probably a million cubic feet per day is being fed through the natural gas mains of various cities in the Middle West and being dissipated into the atmosphere through thousands of chimneys. Steps should be taken at the earliest possible moment to secure for the army and navy the right to process all supplies of natural gas containing usable quantities of helium before this gas is distributed. The details of such a procedure will require careful study and for this purpose an Argon Conservation Committee consisting of a representative of the navy, a representative of the army and a representative of the Bureau of Mines was appointed last August by the Aircraft Board and an adequate allotment to cover its expenses recommended. For various reasons effective action by this committee has seemed impossible until very recently. It is now hoped that the committee can proceed with its work in the near future.--Aerial Age, 8/11.

A ZEPPELIN SECRET REVEALED.-To many people one of the chief minor mysteries of the war centered round the means whereby our authorities were made aware, well in advance, of a projected airship raid against this country. That they were so informed in some manner or other soon became obvious to all, at least in the London area, for it was seen that on the nights upon which raids occurred the searchlights were not practiced at dusk. On one occasion, we can remember, it was confidently asserted that the warning was received of a probable raid almost twelve hours before it actually took place. The mystery has now been solved, and that by one of no less authority than Lord Weir himself. It was quite a simple matter after all; the Germans told us they were coming! Their airships were guided across the North Sea by means of directional wireless on a system involving the sending out of frequent signals from the airships themselves. These signals were picked up by the German wireless stations, which thereupon transmitted to the vessels signals indicating their exact position. Unfortunately for the enemy we also could pick up the signals sent out by the airships, and just as readily as the Germans determine therefrom their position. We thus always knew when they were coming and where they were coming from, and arranged our defences accordingly. Our own directional wireless system, perfected late in the war, avoids this serious military objection to its use. The directional coils are carried by the aircraft, which, picking up signals from home stations, is able to locate its position without telling it to the enemy. It would have been employed, it is confidently believed with success, to guide the two Handley-Page four-engined machines which were ready on November 8 to fly from this country through the clouds to Berlin and back.—The Engineer, 7/25.

The Cost Of A Big Airship. In the British House of Commons recently, Dr. MacNamara, replying to Lieut. Commander Kenworthy, said: “The cost of constructing an airship of R-34 type is approximately £350,000. The cost of the housing shed at East Fortune, together with extensions and wind-screens, is approximately £166,000. Fourteen officers and 400 men are required at the station for handling, berthing, cleaning airships, etc. The estimated total monthly cost of the airship when in commission depends on the distance flown. "Taking as basis 8000 nautical miles per month at a speed of 40 knots, it amounts to about £2600 at current rates for cost of petrol, oil, and gas. This figure includes the wages of crew, and also one-fourth the total pay of the personnel required for handling.

etc., as this latter is adequate for maintaining four airships in commission. No further airships of this class are under construction, but six of improved types have been ordered and are in varying stages of construction. Work upon them is being continued. --Shipping, 8/9.

PLAN CABINET AIR OFFICER.—Combination of the army, navy, marine corps, and postal air services into one separate department, headed by a Secretary of Aeronautics, who would be a Cabinet officer, is proposed in a bill introduced to-day by Representative Curry of California.

The department would have control of the development of commercial aviation and the issuance of licenses to civilian airmen. The Secretary of Aeronautics would be appointed by the President, confirmed by the Senate, and receive a salary of $12,000.

A feature of the bill is its provision for an aeronautical academy to train fliers. The establishment of aircraft factories is also provided for. The operations division of the department would prepare plans for national defence and mobilization.-N. Y. Times, 7/29.

ELECTRICALLY-HEATED CLOTHES FOR AIRMEN.-The extreme cold encountered at the higher altitudes makes it necessary to provide electricallyheated clothes for airmen, at least in the instance of most military machines which offer no protection to the passengers. The energy required to heat these suits is generally around 80 watts, disposed as follows: Helmet, 20 watts; each glove, 16 watts; each moccasin, 14 watts. The energy is supplied at 12 volts, either from a storage battery or from a small fan-driven generator of streamline shape mounted on the airplane, the fan being rotated by the passage of the plane through the air. The heating elements are flat loops of resistance wire spaced about seven per inch and about 9/32 inch wide per row. They are machine-sewed on a cotton cloth base, the cotton thread being carried along the top and bottom of each row of loops parallel to the horizontal axis of the row. Flexibility results from this mounting, and the base can be stretched or crumpled at will without danger of breaking the wire. Each heating element is composed of two bare wires in contact with one another throughout a considerable part of every loop, so that if a break occurs in any one wire, the effect is merely to force the small amount of energy concerned through a conducting path of smaller cross-section between the break and the near points of contact.—Scientific American, 8/2.

Navy AVIATION Division DISCONTINUED.-Admiral William S. Benson, Chief of Naval Operations, issued instructions on July 22 discontinuing the Aviation Division of the Office of Naval Operations and distributing its various activities among the bureaus of the Navy Department. Capt. T. T. Craven, Director of Naval Aviation, under the new arrangement will occupy the position of a liason officer. In his instructions Admiral Benson calls attention to the fact that the plan of the office of Naval Operations embraces the following divisions of work: Planning Division, Matériel Divison, Intelligence Division, Communication Division, Inspection Division, Operating Forces and Files and Records Division. He directs that the Planning Division absorb the Aviation Section, the Submarine and Mining Section, and Gunnery Exercises and Engineering Performances Section, and that the matériel of these sections be handled by the Matériel Division of his office. He also directs that the administration of personnel and training matters be handled by and directly under the Bureau of Navigation, and that the operations of submarines and navy aircraft be administered under the Division of the operating forces of his office.

The discontinuance of the Aviation Division entails the distribution of all activities and follows the navy system of separating the administrative from production and operating requirements. It would seem to be in line with

the purposes of the proponents of an air department, whose strongest argument is that aviation production, design and experimentation should be centralized and that operation should be handled by bureaus in the army, navy, postal service, etc. Admiral Benson's instructions will make the Bureau of Construction and Repair responsible for construction of airplanes and airships, the Bureau of Steam Engineering for the design and production of engines and instruments, and the Bureau of Ordnance responsible for supplying the armament. It will also call for the reassignment of some 18 officers now attached to the Aviation Division.

The action of Admiral Benson will probably result in much discussion as to whether the specialized service of aviation can be made to function and progress under the new arrangement as it has most certainly functioned and progressed as a separate division in the office of Naval Operations. The change will be watched with more than ordinary interest for the reason that the air services as recognized arms of the fighting forces of all nations are just at present under the widest public attention and, too, for the reason that European nations are already abroad introducing their air navigating machines in foreign lands, particularly in South America. The matter of Admiral Benson's instructions is so recent that there has developed little opinion of the desirability of the change among the chiefs of Navy Department Bureaus.-Army and Navy Journal, 8/2.

RELIABILITY OF SERVICE BY AIR.— Probably no subject has been so widely written and talked about in recent months as that of civil aviation, the very idea of which had been banished from our minds during the war. Fares and freight-rates, speeds, weights carried, comfort and safety have all had their share of attention from technical or non-technical writers. These questions in reality hang one and all upon reliability. The business man will long since have agreed on the utility and advantages of air transport, but when its reliability comes up for comparison with that of the railway train he shrugs his shoulders. Starts are planned and not carried out “owing to weather” or engine trouble." Accidents happen. Though commercial flying will, in my opinion, be well supported by the public, there is still a large section which calls for statements on this question, and not without reason.

There are difficulties-serious problems—to combat. The two chief ones are adverse weather and engine failure, in that order because the former is much more serious. We can improve engines but not our climate, though even this is not a serious problem outside of northern latitudes.

Multiplicity of engines on one machine is a factor making for reliability, where the machine is designed to fly on anything above half of its engine power. Advanced as is the modern internal combustion engine it is not perfect, and when two or more are fitted a margin can be relied on in case of failure in one of the number. It requires more power to take a machine off the ground than to maintain it in the air. Every pilot knows this margin of power, with which he can dispense once his wheels have left the grass.

The motorist may ask, “Why all this trouble with aircraft engines when I have run my car 40,000 miles without a single breakdown?” In an aircraft engine it goes without saying that weight is reduced to the last ounce, but it is doubtful if the average motor owner realizes to what figures this has been achieved. The world-famous Rolls-Royce 40-50 h. p. 6-cylinder automobile engine weighs 11 lbs. per h. p. This firm's latest 350 h. p. aeroplane engine approximates 3/2 lbs. per h. p.! More important than this reduction of weight is the question of “revs.” Ninety per cent of the running on a Rolls-Royce car is done with the engine turning over at about 400 r. p. m. The aeroplane demands four times that rate of revolution: the fact is, it cannot afford to carry an engine weighing more than 3/2 lbs per h. p. and that engine must develop practically its last ounce of h. p. the whole time. If on every outing a car engine were run for three or four hours at

1600 r. p. m. it would soon give trouble: how much more, then if it were lightened by 75 per cent in addition to being continuously run at that speed.

Multiplicity of engines, however, will ultimately overcome not engine failure but failure due to engine breakdown. If the modern aircraft power unit possesses a considerable factor of reliability, two units on the same machine double that factor, and so on almost in proportion. The HandleyPage which flew from Ipswich to India was a standard Berlin Bomberour Atlantic entry is another—fitted with four 350 h. p. Rolls-Royce, totalling 1400 h. p. Much as one may rely on modern engines, on one unit of 1400 h. p. the fight would not have been completed-at any rate without weeks of delay en route. Engine trouble dogged it on many important stages, but these were always completed on the remaining units. If an engine fails it usually fails completely, and the only way to allow for failure is to split up the total power into several independent units. The harshest critic with any knowledge of recent performances in the air could hardly say that more than one out of four average engines to-day will give trouble on a 34 hour's flight. Multiplicity of engines will therefore save the situation as far as engine failure is concerned, by eliminating the inconvenience, not to say danger, of involuntary descents en route.

Weather as a flying problem may be divided up into four sections. Wind was once considered an insuperable difficulty. Now nothing short of a hurricane need delay the start of a journey. Rain and snow are unpleasant but not really dangerous. Progress in aerial navigation will soon enable us to fly above clouds, descending only to land at our destination. This has been proved by Zeppelins during the war. January 31, 1916, will be remembered as one of the worst raids on England, yet in parts of Yorkshire then bombed there was a snowstorm raging. Thunderstorms affect compasses, but they are never acco

ccompanied by fog or even clouds connected enough to obscure any considerable area of ground. In daylight they can be surmounted, as they rarely stretch above 9000 feet. They are “local,” to use a meterological phrase, and if encountered on a fight they can be avoided if not surmounted. One young pilot known to me describes a patrol during a thunderstorm near Dunkirk as one of his most fascinating flights. He even thinks we ought to run special pleasure trips on those occasions to let people see the glory in those great pillars of thick greasy cloud rising from a murky gloom at 1000 feet to pinnacles of dazling white in the sunshine at 8000.

By night thunderstorms do present a difficulty at present apparently insurmountable. But then they are' rare, and perhaps that is why they have not yet been tackled seriously.

The paramount problem of all-weather flying to-day is fog--the airman's last, worst, and most deadly enemy. With it might be classed Scotch mist, which is almost as bad. It is possible in a safe machine of some inherent stability, to leave the ground in fog and rise through the bank, which rarely stretches above 1000 feet. Once above it, so much was learnt of navigation over open sea during the war that there is little difficulty in steering a course by compass and reaching the neighborhood of one's destination by dead reckoning. But there our pilot is faced with the real problem—how to locate the actual aerodrome and enter the fog again to perform the delicate operation of landing? Research, experiments, tests are being carried out unremittingly to reach a solution, and all this work will bear fruit. Among the suggestions is one to utilize captive balloons over every aerodrome, well above the fog bank, with perhaps an observer in the car in communication by phone with the ground below. He would signal directions to approaching aircraft, communicating instructions from the aerodrome manager. On the balloon cable would be streamers indicating height, according to a predetermined scale, and wind direction, though fog is not often accompanied by enough breeze to signify. These would give the oncoming pilot an idea of the height of fog above the surface of the aerodrome, for an aneroid set at his starting point cannot be relied 'on for a place two or

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