pleting their journey. On Thursday, January 23, the mail was brought south as far as Silverside, Del., in the face of a 65-mile gale at an altitude of a few thousand feet.

The fastest time of flight carrying the mail from College Park to Belmont Park, N. Y., a distance of 218 miles, was I hour and 30 minutes, and the slowest time for a continuous flight was 4 hours and 56 minutes. The average time is 2 hours and 40 minutes. The common experience of the users of aeroplane mail is that a letter posted in the down-town stations in Washington as late as 10.50 a. m., and leaving the aviation field at 11.30 a. m., is usually delivered between 4 and 4.30 in the afternoon, which is in ample time before close of business.

Extension of Service.-The greater distance between the points on an aerial mail route the greater is the service rendered to commerce and the greater is the patronage of the line. A mail service leaving New York at 6 in the morning and arriving at Chicago before 3 o'clock in the afternoon, in time to connect with carrier deliveries, will advance the mail between the two cities by 16 hours over any train dispatch that can be made after the departure of the Twentieth Century Limited from New York at 2.45 p. m. The department desires to establish this line immediately and extend it west to the foot of the Rockies during the coming fiscal year, with the view of reaching the seaports of Seattle and San Francisco, if Congress authorizes the appropriation necessary. The air mail time between New York and San Francisco will be less than 40 hours. It is desired that this transcontinental trunk line shall be tapped by lines from Minneapolis, St. Paul, St. Louis, Kansas City and other points, and ultimately by a line from Boston, via Albany, Buffalo and Detroit, to Chicago.

A north and south trunk line from Boston to Atlanta should likewise be established, with an ultimate extension from Boston to Montreal, Canada, and from Atlanta, via Key West, to Habana. Based on the accurate cost accounting kept in the operation of the Washington-New York air mail line, the cost of an east and west trunk line from New York as far west as Omaha and a north and south trunk line from Boston to Atlanta has been carefully estimated at $1,600,000. To this should be added $400,000 for several essential feeders that would connect up Detroit, Minneapolis and St. Paul, St. Louis, Kansas City and other points, and would admit of an extension as far west as Salt Lake City, this extension, however, dependent upon the extent to which the government equipment can be transformed into strong and safe mail-carrying machines.

For this reason it would be very desirable to obtain an appropriation of $2,000,000 for the ensuing fiscal year.-Flying, March, 1919.

THE SIGHTING PROBLEMS OF THE AVIATOR.-One of the greatest difficulties experienced by aerial fighters, when machine guns on airplanes came into general use, was to hit the target aimed at. This may seem, to the uninitiated, like a bald statement of poor marksmanship, but in reality it is not. As a matter of fact, to bring down an enemy machine without specially designed sights is nothing more nor less than pure, unadulterated luck.

For instance, imagine two machines passing each other along parallel lines, 100 yards apart, each traveling 100 miles per hour. You are equipped with a machine gun firing 700 shots a minute-11 each second-the bullet traveling at the rate of 4,960 feet per second. If you took a dead aim at the enemy machine your first bullet would miss its mark by 18 feet, and the second bullet, coming I-II of a second behind the first one, would miss its mark by 45 feet.

To offset this, and to make aerial fighting more of a science, ring sights were devised. These sights consist of two rings, a small one, representing the bull's eye, and a larger one encircling it, representing the line of flight of the bullet. If aim is taken when the enemy machine is crossing the outer

circle (the hostile aircraft being 100 yards distant and traveling at the rate of 100 miles per hour) the bullet would reach it as it enters the smaller ring, constituting a direct hit.

But this only compensates for the speed of the enemy machine. You still have to make allowance for the speed of your own machine. This is done by means of the Norman Compensating Foresight, a bead sight fitted to a swivel, with a wind-vane swinging on one side, which raises and lowers the bead, and revolves on its axis, according to the pressure of the wind in the slip-stream.

The most wonderful of all sights, however, is the Aldis Optical Sight, used for stationary guns when firing through the blades of the propeller. This sight was invented by the two Aldis Brothers, manufacturers of lenses, who, under subsidies from the British Government, have brought the making of high grade lenses to a higher point than the German's finest workmanship.

The Aldis sight is virtually a telescope which neither magnifies nor diminishes, and which, unlike an ordinary telescope, can be used with the eye several inches from the end of the tube.

SILHOUETTES ILLUSTRATING THE USE OF THE RING BACK-SIGHT WITH THE WIND-VANE FORE-SIGHT.

(The former is set for the estimated speed of the adversary, while the latter automatically compensates for the speed of the plane on which it is mounted. The upper row of silhouettes is for a range of 200 yards; the lower row shows the same objects at 100 yards.)

When looking through this tube at a distant object the effect is exactly as though one were looking through a napkin ring-the object appears the same whether it is seen through the tube or outside it-but, apparently suspended in the air, is a ring sight. The peculiarity is that the ring is seen with its center on the spot at which the tube is pointing, no matter where the eye is placed. If the eye is moved sideways the ring appears to move with it through the telescope, so that the direction in which the tube points is always toward the center of the ring.

The tube, when fixed rigidly to a gun, thus constitutes a sight which offers practically no obstruction to the view, and which shows instantly the spot at which the gun is pointing, without the necessity of alining the eye on a front and back sight. The effect produced on the pilot of seeing an enemy machine flying into this ring suspended in mid-air is quite startling.

One advantage of this sight is that it can be used with both eyes open. One eye sees the object and the circle through the tube, the other eye

sees the object direct. The effect, after a little practice, is that the object is seen as clearly as though there were no sight at all.

The tube is about three feet long and about three inches in diameter, and contains five specially constructed and arranged lenses.

One fact about aerial fighting, however, which has never been mentioned is that, after the first sight has been obtained, the pilot never uses his sight at all. He watches the bullets-literally! That is, he watches the tracer ammunition. One in every three shots is a tracer-a bullet which trails a little path of smoke; and it is much more interesting to watch the tracers than it is to keep the eye on the sights. Most pilots would like to use all tracers if they could, for they kill as readily as the regular bullets. But, unfortunately, tracer ammunition is dirty, and will soon 'choke the bore of the gun. As it is, a great many pilots load their magazines and belts with every other one a tracer, though it is strictly against the rules. The temptation though is too great to be resisted.

The tracer is made the same as the ordinary bullet, except that, in the end, is a small quantity of magnesium which ignites. It is not quite accurate, as it is lighter and drops a little in its flight, but it serves its purpose wonderfully.-Scientific American, 15/2.

MISCELLANEOUS

300,000 IN A. E. F. BY JULY 1, IS PLAN.-General Pershing Announces Eighteen Divisions to be Returned by that Time.-Announcement by General Pershing's chief of staff that eighteen National Guard and National Army divisions were scheduled to sail from France before July 1 apparently confirms reports which have been current here that the expeditionary forces were to be reduced to a total strength of 300,000 by the end of the current fiscal year.

Calculations in the various War Department bureaus, it is said, have been based upon the 300,000 strength in figuring on the maintenance of the army abroad after July 1.

The announcement from France indicates that in addition to the seven regular divisions now in France and into which presumably men desiring to remain temporarily are being transferred, the American forces after July will include the 78th and 81st National Army divisions and one other division. This would give a nine-division strength for the combatant forces and allow one division for employment as a depot unit.

While the statement from Paris named only eighteen divisions, all others now in France except the seven regular and four National Guard and National Army divisions already are on priority for early return, and have been skeletonized and are returning as casuals.

German shipping, which now becomes available, will be used in the repatriation of the troops. The order of precedence of their return is based on the order of their arrival. The only exceptions to this ruling will be when the availability of rail and sea transportation, the relative location to ports of the controlling military situation makes the exception

necessary.

Troops in the service of supply and labor troops will be returned in the order in which their services can be spared, and as far as possible in the order of their arrival in France.-N. Y. Times.

72,951 DEATHS IN OVERSEAS FORCES AND 34,493 AMONG TROOPS AT Home.— The following statistics showing the number of deaths during the war in the American Expeditionary Forces and among troops in the United States have been prepared by Statistics Branch, General Staff, War Department.

Figures for the United States are from April 1, 1917, to February 14, 1919; for the American Expeditionary Forces, to February 16, 1919.

Source of information: Current statistics section and medical records section, Division of Sanitation, Medical Department.

The destroyer Ingram, said to be the first vessel in the United States Navy named for a non-commissioned member of the service, was launched at the Fore River plant of the Bethlehem Shipbuilding Corporation at Quincy, Mass., late last week. It was named after Osman Kelly Ingram, chief gunner's mate of the destroyer Cassin, who was killed when that vessel was torpedoed by a German_submarine. The Ingram was christened by the sailor's mother, Mrs. M. E. Ingram, of Park City, Ala.-Shipping, 8/3.

CONSCIENTIOUS OBJECTORS REFUND $8,589 ARMY PAY.-The War Department authorizes publication of the following statement:

The War Department has received from conscientious objectors as refunds of pay the sum of $4,319.82. Conscientious objectors have also refunded their pay through the channel of the Y. M. C. A. to the amount of $270. The Friends' Society had received up to February 15, $4,000 designated for Friends' reconstruction work from conscientious objectors unwilling to accept pay from the army. This makes a total of $8,589.82 thus refunded.—U. S. Bulletin, 28/2.

PROGRESS IN FINDING JOBS FOR RETURNED SOLDIERS AND SAILORS.-More than 75 per cent of the returning soldiers and sailors who need assistance in finding employment are being placed in jobs through the United States Employment Service, the Department of Labor announces.

The employment service is finding that of the average 60,000 men weekly discharged from the army, 30 per cent, or 18,000, must find new work, and that 20 per cent of the total, or 12,000, each week are being placed in employment through the Federal Employment Service and its co-operating welfare, civic, and other organizations. The placement figures are based only upon the reports of men known to have been placed, and it is estimated that at least 5 per cent more are being helped to jobs through the employment service. There is a much higher percentage of men needing new jobs among the soldiers from the industrial centers than from the agricultural districts.

The employment service is conducting its soldiers' placing work through offices and agents in all demobilization camps and 2000 special bureaus for returning soldiers, sailors, and war workers in the towns and cities. The bureau for returning soldiers and sailors of the United States Employment Service in the District of Columbia, for instance, has thus far received 2113 applications from soldiers for jobs, and of this number has placed all but 50.-U. S. Bulletin, 28/2.

CURRENT NAVAL AND PROFESSIONAL PAPERS

UNITED STATES

REVIEW OF REVIEWS. March. The Navy's New Task, by Secretary Daniels.

ATLANTIC MONTHLY. March.-The Territorial Claims of France, by René Pinon. The Peace Congress and the Balkans, by J. O. Bourchier. Bolshevism: a Liberal View, by H. W. Stanley.

HARPER'S MAGAZINE. March.-How the War Was Won, by General Malleterre.

TIMES CURRENT HISTORY. March.-Heroism of Torpedoed Transports (Official Narratives). Sinking of the Viribus Unitis, by Lieut. Col. R. Rossetti.

WORLD'S WORK. March. At Home with Admiral Beatty, by Francis T. Hunter. The Surrender of the German Fleet.

FLYING. March.-Value of Dirigibles for Aerial Transports, by Henry Woodhouse. Regulations of Future Air Traffic, by Alan R. Hawley. Aero Radio Surveying and Mapping, by John Hays Hammond.

PAN AMERICAN BULLETIN. December.-Latin-American Trade-A Comparative Survey.

SCIENTIFIC AMERICAN. March 15.-The North Sea Mine Barrage (I), by Capt. Reginald R. Belknap, U. S. N. Future of British Flying, by C. H. Claudy. Reflecting Prisms-Their Use in Place of Mirrors, by Naval Instructor T. V. Baker, R. N.

GREAT BRITAIN

ENGINEERING. Feb. 21.-The Industrial Progress of Japan. The Development of Airplanes in the War.

LAND AND WATER. Feb. 20.-Lord Jellicoe's Case, by Arthur Pollen.