Two lines of effort, demanding very different modes of procedure, lay before the Council in entering upon its war services. Many new scientific methods, unfamiliar in the United States, had been developed and successfully applied by our Allies during the war. It was a matter of the first importance that we should lose no time in profiting by such advantages, which demanded for their application the organization of new services in the army and navy, and the enlistment of large numbers of scientific men for service at home and in the field. In the second place, experience abroad had shown the necessity of conducting researches for the solution of military, naval, and industrial problems, even after war had begun. It goes without saying that such researches, which demand much time and thought, should have been initiated years before the outbreak of war. But as preparedness for national defense had been as sadly neglected in its scientific aspects as on its more obviously military side, there was no alternative. In Germany, where a short war had been expected, the men of science had been called upon after the outbreak of hostilities to develop new processes and to provide substitutes for commodities cut off by the blockade. In France and England, researches conducted under the disturbing conditions of war had been equally successful. It was plain that we in the United States must lose no time in taking advantage of our great national asset of scientific men and laboratories.

At this point a fundamental principle in the policy of the National Research Council should be mentioned. In spite of its establishment for the promotion and utilization of scientific research, the Council took the stand from the outset that in time of war the proper procedure is to adopt and immediately to utilize at the front the best available military device for the accomplishment of any purpose in view, before attempting to develop a more effective means of serving the same end. When men and means were available, researches for the improvement of such devices, or for the development of new ones, might advantageously be initiated in many cases, but there

could be no excuse for delaying action in order to await the outcome of these researches. In time of war there can surely be no justification for delays due to a desire to gratify personal or national pride in inventiveness or originality.

When a scientific investigator undertakes any piece of research, his first act is invariably to ascertain just what work has already been accomplished in that field. It goes without saying, therefore, that an organization composed of scientific investigators must proceed in the same way in attacking any large problem involving research. Moreover, it must lose no time in arranging for close coöperation with the scientific men of other nations concerned with the same problem.

Accordingly, the President of the National Academy, accompanied by the Chairman of the Committee appointed by the Academy to organize the Research Council, made a preliminary visit to England and France in August, 1916, in order to learn the general character of the war services rendered by the scientific men of these countries. They found the investigators, with whom they had coöperated for many years in scientific research, actively engaged in the study of war problems. Eminent physicists, always successful in research and prolific in new ideas, were giving much attention to the improvement of airplanes, which were so greatly increased in efficiency in England during the war. Others were attacking the submarine problem, the full menace of which has finally become known to the public through the recent articles of Admiral Sims. The Astronomer Royal, most of whose staff was at the front, was utilizing the facilities of the Royal Observatory at Greenwich for the rating of chronometers and the adjustment of field-glasses. On the roof was a range-finder for the location of Zeppelins and German airplanes, which had recently dropped bombs in the Observatory garden. Distinguished physiologists were seeking means of alleviating the new sufferings imported by the Huns into warfare. In fact, all British men of science, if unable to enlist for duty at the front, were devoting themselves to any available war service.

In France the activities of the men of science, who responded to the earliest call for the national defense, were no less impressive. The Minister of Public Instruction, himself an able mathematician and member of the Institute, had organized a strong group, which dealt with a great number of war problems. Some of its members were the first to conceive and to carry into effect the method of sound-ranging, a brilliant application of physics in warfare. Leading physicists and astronomers with whom American investigators had long been associated in the work of the International Union for Coöperation in Solar Research, were prominent members of this group. The Paris Academy of Sciences was also contributing largely through its members toward the solution of scientific questions of both military and industrial importance. Such examples afforded a powerful stimulus to those American investigators who felt that the continued lawlessness of the Germans must soon identify our interests with those of the Allies.

On the day preceding the entrance of the United States into the war, the following cablegram was sent by the National Academy of Sciences to the Royal Society of London, the Paris Academy of Sciences, the Accademia dei Lincei of Rome, and the Petrograd Academy of Sciences — leading scientific bodies, then engaged in the study of war problems, with which the National Academy had coöperated for many years in scientific research.

The entrance of the United States into the war unites our men of science with yours in a common cause. The National Academy of Sciences, acting through the National Research Council, which has been designated by President Wilson and the Council of National Defense to mobilize the research facilities of the country, would glady coöperate in any scientific researches still underlying the solution of military or industrial problems.

Steps were also taken to despatch a group of seven scientific investigators to France and England for the study of war problems and the arrangement of effective means of coöperation.

The members of the Committee sailed early in May, 1917, and were most cordially welcomed and given information of great value.

The response of our foreign colleagues to our offer of cooperation was immediate and effective. France sent to the United States an able group of investigators, and both England and Italy did likewise. The French members brought with them a large collection of instruments and devices developed in France for military and naval purposes since the outbreak of the war, which was invaluable in connection with our work.

Just at this time the submarine danger was at its height. Shipping to the amount of 900,000 tons was sunk by the Germans in April, 1917, and the British Government was extremely doubtful whether this menace, the most serious of the war, could be overcome. As Admiral Sims has recently

pointed out, quick action was essential. The depth charge had already been invented, and naval officers all agreed that if the submarine could be definitely located it could be easily destroyed. Thus the problem for the scientific investigator was to devise a means of determining the exact position of a submerged submarine. While it was true that the results of their researches might not be obtained and applied in time, it was equally clear that no effort should be spared, even at that late date, to devise the apparatus so urgently required. If the vigorous action of the combined navies of the Allies should succeed in alleviating the menace, without wholly overcoming it, there might be time to develop a detection method which would permit the finishing blow to be dealt. Fortunately for the cause of the Allies, the convoy system, then regarded by the masters of merchant ships as impracticable, was soon successfully applied. But this outcome could not be foreseen, and the men of science were in duty bound to contribute their best efforts without delay.

The National Research Council accordingly organized a conference on the submarine problem in which the foreign repre

sentatives, with officers of the Navy Department, and the physicists and engineers who had already studied the question in this country, participated.1 In order to make clear the general nature of the methods discussed, the following brief description of the apparatus employed may be of service.

Submarine detection devices are of two principal classes: listening apparatus, on the principle of the microphone or the stethoscope, and instruments analogous to searchlights for use under water, in which the beam of light is replaced by a beam of sound. A simple physician's stethoscope, if placed under water and connected to the ear by tubing, will render audible the sound from a rapidly moving submarine at a distance of a mile or more. Indeed, a small piece of rubber tubing, if substituted for the stethoscope, will serve very well as a sound detector. By connecting with the ears two stethoscopes, at opposite ends of a supporting bar three or four feet long, the direction of a moving submarine can be determined with considerable accuracy by rotating the bar in a horizontal plane and utilizing the same binaural discrimination with which we ascertain the direction of sounds without apparatus. By refining this apparatus, it is even possible to employ it on a submarine destroyer moving at a speed of several knots, in spite of the local sounds due to the destroyer. However, the method is seriously limited in actual practice; it cannot be used on vessels moving at high speed, it cannot detect submarines lying at rest or moving at low speed, and confusion may result from the presence of several surface vessels, as in the case of a convoy.

We therefore look for assistance to an entirely different device. A beam from a searchlight is quenched by a short thickness of water, but a beam of high frequency sound waves

1 Three able groups of investigators were already at work on this question in the United States under the Bureau of Steam Engineering of the Navy, and both the Naval Consulting Board and the National Research Council had taken part in promoting studies of the submarine problem.