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had reached a stage of development little known outside of military circles. Beginning in the fall of 1917, with a single school of aerial photography at Langley Field, we had within a year four schools which had graduated 2300 men, while 700 were still in training. There are, besides, 2000 airplane pilots and observers who have had complete instruction in aerial photography.

Writing in Flying for April, Captain M. A. Kinney, Jr., states that our camera men are able to make as many as 90 per cent. "good" pictures at altitudes of 6000 feet. These men have also learned how to make accurate "mosaics" by triangulation. With the K-1 camera they can in one continuous trip at an altitude of 10,000 feet take enough exposures to cover an area of about 200 square miles. This is photographic mapping by wholesale! The various photographs, gathered as the result of a mapping trip, can be pieced together in an accurate mosaic by an absolute method of triangulation. When the map is completed it may be turned over to trained draftsmen, who trace it, and by a system of interpretation, work in woodlands,

surveying is thus reduced to hours. Captain Kinney suggests several directions in which this aerial map-making may be turned to good advantage in our commercial and industrial life:

that suggests itself for successful commercial development is the mapping of small areas for real

An interesting field for aerial photography

estate projects or proposed industrial sites. It is a well-known fact, that where new buildings are to cover large areas there never are good maps of plant and neighboring territory. Because of the lack of good maps, sometimes three or four months of valuable time must be lost before grading operations can be commenced. Say, the area for real estate or industrial development is forty square miles in size. By aerial photography a map just as accurate as that produced by the surveyor and far more comprehensive can be made available within forty-eight hours after the flight to take the exposures. This in itself is made a wonderful asset to the ordinary business proof positive that aerial photography can be man.

Aerial photography will be of especially great value in forestry work. Months and even years of time are now being spent by so-called timber cruisers who travel through forests with pedometer and pack mule to make rough surveys. Their reports naturally can't be very accurate. Think

on the other hand how very valuable a large photographic map accurately scaled on which practically every bush and tree is shown of a large tract of wood, would be to the owner.

A mosaic of such a forest would show at a glance all virgin tracts of young trees which could not be considered of commercial value, all bush-land, fire tracts, so-called "dead-lake" areas, etc. We have even specially trained men who by close study of foliage as shown on the photographs can tell what species of tree predominate in the area. Also by means of oblique photographs as adjuncts to those taken vertically one can determine the general height of the trees and their denseness. From this one can see that a concern with photographic data such as that obtained by aeroplane and contemplating the purchase of certain areas could estimate quite closely the number of feet of lumber that could be obtained from the tracts and know what obstacles would be met in cutting and transporting the timber.

Railroad valuation suggests another extensive use for aerial photography. It is a fact that all. large railroads spend thousands of dollars yearly for the hire of crews of civil engineers who

spend all their time making valuation surveys. These jobs extend into years and by the time they have finished the valuation of a certain section a good part of their data is obsolete because of changes and improvements. I know, for example, of one road that for six years has been trying to get a complete valuation report by the survey method of 200 miles of its property and though six years have passed since the work was begun only 100 miles have been covered. A large number of changes can occur in six years, so one can see just how really inadequate a report of this kind is to a railroad company.

On the other hand, an aeroplane traveling above the right of way could quickly cover any section desired and map out not only the railroad property, but also all land for a half mile on each side of the tracks. All telephone poles, ties, waste material, signal apparatus, culverts, crossings, bridges, etc., would be shown and the copies of the linear maps would be of great convenience not alone as a valuation report easily visualized but of untold benefit to various departments in checking up material and equipment along the right of way. Such maps could easily be kept up-to-date by periodical re-mapping trips.

TARGET PRACTICE WITH MACHINE-GUN CAMERA

con

struction and use of the new gun camera in a recent number of the New York Sun, Capt. Harry J. Devine, who assisted in its development, tells us it was offered to the Government by one of America's photographic manufacturing companies from a purely patriotic motive. "This gun camera, as brought to its present state, is absolutely American in theory, design and manufacture, and we are proud of it," he says. "It is only another of the unexpected developments of war work and its future use in peace times is unlimited."

The American type of gun camera, as finally perfected, weighs only thirteen pounds, with a lens barrel eight inches in length and two inches in diameter. It is attached directly to the gun, with its magazine of film in place of the cartridge magazine of the machine gun. It is so simple that in thirty seconds the film magazine can be substituted in the air for the cartridge magazine and the gun can be used in combat. The camera takes 100 exposures of film on one loading, which is equivalent to 100

In order to obtain the automatic action of a machine gun, it was necessary to find a substitute for the exploding gases which operate the ejecting and cocking mechanism; and a hand-wound spring like a phonograph spring, attached to the five-inch film reel shaft through the shutter mechanism, was adopted. As in shooting in the air, it is necessary to aim the plane itself in order to bring the gun to bear on the enemy; skill in maneuvering, daring and nerve, and accuracy are essential to assure the destruction of the enemy and protection for the pilot, his observation records, and his plane. Shooting a machine gun in the air, therefore, is far different from similar target practice on the ground; and it was to test these necessary qualities in an aviator that the gun camera was used. Captain Devine says:

The recording of the shots is made through a glass plate called a graticule, placed in the barrel of the focal plane in contact with the film, which is marked with vertical and horizontal lines pass

ing through the center and one small circle indicating the bull's eye of the target, while two larger circles indicate the outer field covered by the camera. These marks are impressed upon every film and consequently good and bad shots are recorded accurately in every phase of the aerial work.

The most recent development of the camera was the application of a timing attachment by which a watch face, attached outside the device, is photographed through reflection on the same sector of the film which records the shot. Thus, it records the image of the target, showing the exact location of the other aeroplane, and shows to the fraction of a second when the shot was made. By this means two, instead of one, aviators, may engage in practice combats, with a perfect record of their work and accurate register of the proficiency of each.

The tremendous speed at which machines are

flying and the position of the opposing machines at the instant of firing a bullet (making exposure), must be reckoned in the crediting of hits. The accompanying photograph shows a perfect bull's eye, for the plane photographed is flying directly into the field of the machine gun bullets, the margin of speed carrying it forward so as to be hit in a vital part.

This is only one of the many photographic marvels which Uncle Sam had up his sleeve for the Hun; and it is the lifting of the ban of censorship that enables us to learn of this remarkable invention. All the American Army and Navy flying fields were equipped with the gun camera, and 1400 were manufactured for the service up to the date of the Armistice.

OME interesting reminiscences of Col

onel Roosevelt are given in Nuova Antologia (Rome) by Signor Mayor des Planches, who was Italian Ambassador at Washington during the Roosevelt administration.

The former Ambassador recalls especially Mr. Roosevelt's fervent admiration of Julius Cæsar, whom he regarded as the greatest man the world had ever produced. When he requested Signor Mayor des Planches to transmit for him to the Italian historian, Guglielmo Ferrero, then on a visit. to the United States, a personal invitation to be his guest at the White House, he indicated among the motives that made him wish to be better acquainted with the historian of Rome, the hope that he might induce Signor Ferrero to modify a little his judgment of Julius Cæsar, a judgment he considered to be unjust.

In conversation, Mr. Roosevelt was versatile, vivacious, ready, copious, and agreeable. Reminiscences, anecdotes, allusions, flowed from his lips uninterruptedly. After the diplomatic dinners at the White House, he would invite the Ambassador (not the ministers plenipotentiary, much less those of lower rank) into a small reception room to take coffee or to smoke. This room was soon called the "Café des Ambassadeurs," after the famous resort in Paris. On such occasions Roosevelt was not merely brilliant, he was scintillating. The different literatures, history, archæology, and art, furnished the

material for his talk, and he set in motion all his arts to please, to fascinate, and to inspire admiration.

On the other hand, the Italian writer does not find that he was a really great orator, although he was an abundant speaker. His enunciation was somewhat labored, even in ordinary conversation his utterance was occasionally such as to give the impression that as a child he might have stammered and had later overcome this defect. At least this might have been inferred from the fact that certain words seemed to cost him an effort, and led him to contract sharply his facial muscles, showing his teeth, which were large, with a peculiar expression that was quickly seized upon by the caricaturists. "A pair of glasses over a set of teeth," as was said in France.

Therefore in public speaking the writer does not credit him with that even flow of well-phrased ideas which constitutes eloquence, nor that art, perhaps a trifle theatrical, of moving the emotions, that is possessed by William J. Bryan, and which can make the hearers pass in a few moments from tears to laughter, or vice versa. But he was always strong, often subtle, and being convinced himself he convinced others.

He had read much and still continued to do so; even during his Presidential term he found time for this. The writer also tells of his habit of reading aloud to his family in the evenings, commenting on what he had just read and chatting about it.

of the weak and helpless. Furthermore, it proved, that private individuals without political power, could force from an unwilling official class, attention, interest, and finally action, in a righteous and needful reform. The signatory powers were Germany, Austria, Belgium, Denmark, Spain, France, Great Britain, Italy, Luxemburg, Holland, Portugal, Sweden, Switzerland (alphabetically arranged in French).

With the constant pressure of the "Internationale" agitators, a third official Conference was brought about in 1913. It met at Berne in mid-September-less than a year before the unforeseen world-war befell.

Here again only two limited problems were seriously considered:

(1) Night work for juveniles. The rule there decreed is, up to 14 years, none; from 14 to 16, only in a special crisis not recurrent nor to be foreseen. The other exceptions are merely for the next few years, until certain industries can be adjusted to the new requirements. No labor harmful to health is included therein. (2) The maximum day for women, and for boys under 16. That is fixed at 10 hours-or 101⁄2 at most, in a total week of 60 hours. This was in various countries a radical reform. In Belgium, for instance, there had been no limit, except one of twelve hours daily for women under 21 and boys under 16.

t

All governments were urged, also, to ordain suitable breaks in any labor day exceeding six hours. Even the exceptional extra service, at urgent need, was limited to an annual total of 180 hours-this only in certain industries, and never in the case of workers under 16.

"Such is the second chapter of the international labor code, or rather, such it would be to-day, had not William II unchained war;" for the convention had not received official ratification by the home governments when the great storm broke.

That ratification may be part of the special recommendations of the Labor Commission, now sitting in Paris, to the Peace Conference itself. M. Turmann calls effective attention to the illuminating fact that this Commission is presided over by Mr. Gompers of the American Federation of Labor, although prior to the war the United States had held aloof from European efforts to internationalize labor legislation.

Every serious student of sociology, or of human progress generally, will find a careful study of this entire essay most profitable. Not less encouraging is the story as an example of the moderate success long ago attained in united action for the common good by practically all the states of Western and Central Europe. It is a happy foreshadowing of the larger future.

HAT knowledge is power and igno

THAT

rance is weakness was illustrated in more than one way by events of the late war. A conspicuous illustration is cited by Prof. Wesley C. Mitchell, president of the American Statistical Association, in an article published in the Monthly Labor Review (Washington). When the war began the Federal Government possessed twenty or more statistical agencies, the weaknesses and especially the lack of coördination of which had been keenly realized even in peace time. These agencies were quite inadequate to the task of supplying the data needed under war conditions concerning national resources of various kinds, and the business of putting the nation on a war footing was seriously delayed by the lack of this statistical knowledge. Hence, says Professor Mitchell:

The Council of National Defense, the Food Administration, the Fuel Administration, the Shipping Board, the War Trade Board, the Railway Administration, and the War Industries Board, sooner or later set up each a new and independent statistical agency to meet its especial needs. The War Department and the Navy Department followed suit. And these agencies, like the war boards which created them, had to be manned with people inexperienced in Government work and unfamiliar with Washington.

Yet the statistical work of the war boards as a whole showed precisely the same defect in organization as the work of the old statistical bureaus, and showed that fault in an aggravated degree. Each new agency worked by itself for a separate board. Hence there was much duplication of effort, and at the same time many important fields remained unworked; the results reached by different agencies could not be readily compared or combined; and the cost was needlessly great. Further, the energy of the new statistical agencies and the haste in which they worked magnified a minor fault of the old system