BRIGADIER GENERAL JOHN W. RUCKMAN-A TRIBUTE LIGHTS AGAINST NAVAL TARGETS. BY MAJOR JOHN S. PRATT, C. A. C. MANY THINGS... BY MAJOR PAUL D. BUNKER, C. A. C. PROFESSIONAL NOTE-ANTI-AIRCRAFT UNITS IN ARMY.... ARMY AND NAVY JOURNAL THE FUTURE OF ANTI-AIRCRAFT ARTILLERY. BY ROBERT V. MORSE, CONSULTING ENGINEER EDITORIAL: Kitchen Police.. Subcaliber Practice. 525 568 582 583 594 595 THE BEATEN ZONE: Adjustment of Fire.... 598 Note on Gunnery Problems.. 600 Correction to "Gunnery for Heavy Artillery (Provisional)”. 600 601 601 of Gun and Target.. 602 Solution of Problem 25. Gunnery-Fire Adjustment.. Solution of Lesson No. 7-Administration-Morning Report... ... .... THE BULLETIN BOARD... INDEX TO CURRENT ARTILLERY LITERATURE. 602 606 612 615 616 618 Published monthly under supervision of the Commanding General, Coast Artillery Training Center, by direction of the Chief of Coast Artillery, under authority contained in paragraph 4, Regulations No. 6, Joint Committee on Printing, Congress of the United States, dated Dec. 17, 1919. Entered at the Post Office at Fortress Monroe, Va., as second class matter. Acceptance for mailing at special rate of postage provided for in section 1103, Act of October 3, 1917, authorized May 8, 1920. All subscriptions payable in advance. Subscription rates: Remittances, articles intended for publication, and communications relating to the management should be addressed JOURNAL U. S. ARTILLERY, Fort Monroe, Virginia. Authors alone are responsible for statements in contributed articles. It is earnestly requested that prompt information be given of changes of address, or failure to receive the JOURNAL. Both old and new addresses should be given. MAJOR F. S. CLARK. C. A. C., Manager and Editor. Just as this issue of the JOURNAL is being printed comes the sad announcement of the death of General Ruckman, on June 7, 1921, at his home, 26 Browne Street, Brookline, Mass., following a sudden stroke of apoplexy. To all of the older officers of Coast Artillery this announcement will be a serious blow, because for many years they have known General Ruckman and have admired and respected his independent courage and his far-seeing vision with respect to all matters concerned in the progress of the Coast Artillery Corps, and the development of Coast Defense. General Ruckman's high attainments need not be enumerated here. They are known even to the younger officers. It is nevertheless especially fitting to pay a personal tribute in the JOURNAL to the man who shared in the pioneer effort of a little group who founded the JOURNAL OF THE UNITED STATES ARTILLERY in 1892, and who, in the face of many discouragements, initiated the awakening of a professional artillery spirit. First Lieutenant John W. Ruckman was the first Editor of the JOURNAL OF THE UNITED STATES ARTILLERY, and his devoted efforts during the first four years of the JOURNAL's existence set a standard which paved the way for the usefulness which the JOURNAL has achieved in the years between, and for whatever service it may render in the years to come. General Ruckman lived to see the creation of the Coast Artillery as it is today, and his own influence was one of the prime factors in that development. The passing of General Ruckman marks in a significant. sense the end of an era. In an article in the JOURNAL in 1912, General Ruckman, in writing of the officers of the generation before his own, said "The swords of many of them have done their last service and have been sheathed and hung upon the wall, but their influence still lives in our ideals." In no truer words could be framed the tribute to his memory which shall be lived in the purposes of those of us who remain, to carry on from where he has left it the work of altruism and of patriotic enterprise in which he shared. Journal of the United States Artillery Vol. 54 No. 6 JUNE, 1921 Whole No. 178 Tactical Organization and Employment of By Major John S. Pratt, C. A. C. INTRODUCTION IN ORDER that a proper conception may be obtained of the raison d'etre of many of the tactical principles and concepts laid down in the following discussion, it is quite necessary that the reader first familiarize himself with the general characteristics of the probable future standard fire control system as conceived by those who have thus far so ably performed the major part of the pioneer work of development. A general discussion of the new fire control system, including both the long and the short range systems, may be found in the remarks of the Coast Artillery Board in reply to a study of the same subject presented by Major W. P. Wilson. The reply in question is included in the August, 1920, number of the JOURNAL U. S. ARTILLERY. The framework upon which an efficient searchlight defense must be constructed is particularly and intimately related to that of the short range fire control system, the more important details of which are referred to and described in Major Quinn Gray's article on "Fire Control," appearing in the April, 1921, issue of the same periodical. The pamphlet, "Tactical Employment of Heavy Artillery (Provisional)," prepared by the Coast Artillery Board should also be read in connection with the subject matter contained in this discussion. Marked improvements have been made in recent years in the mechanical design of searchlights, especially with regard to the structure of the carbons, the constitution and power of the arc, the method of regulating and of focusing the arc, the reflector, the front door, ventilation of the barrel, the mounting of the light, the mobility of lights and the means for controlling and indicating the movements of the light in azimuth and in elevation. These mechanical improvements have effected an increase in the average maximum effective range of searchlights and in their facility and precision of operation and control. Important empirical discoveries and academic investigations have been made bearing directly upon the general efficiency and operation of searchlights, concerning particularly the following points: 1. The relative effectiveness and adaptability of various sizes and designs of searchlights, fixed and mobile, as affecting the determination of the most efficient standard type to be employed for different purposes. 2. The effects that different types of front doors have upon the dispersion, density, intensity and penetrative powers of the beam. 3. The color and form (contraction and expansion) of the beam, as affecting its absorption under varying atmospheric conditions and therefore its penetrative ability and average maximum effective range. 4. Illumination of the foreground and the effect on observation of stray back-reflected light. 5. The maximum period of operation without recarboning. 6. The utility and practicability of the occulter and of distant control of the searchlight. 7. The proper tactical classification of searchlights. 8. The most effective position of the observer relative to the source of light and the equipment that should be provided for the observer. 9. The effects (advantages and disadvantages) of various heights of site on the efficiency of the beam. 10. The vulnerability, protection and concealment of searchlights by day and by night, "in action" and "out of action," under various conditions of atmosphere and when subjected to various forms of attack. 11. Times and occasions for putting searchlights "in action” and "out of action." 12. The blinding effect of searchlights at various ranges and under different atmospheric conditions. 13. The limitations of practicable observation due to interference, as affecting the number, location and employment of searchlights in any particular coast defense area and the total number of targets that can be effectively assigned to a tactical grouping at any time. 14. The effects on searchlights of mist, haze, fog, rain, snow and smoke screens of various densities. 15. Facility of control, extent and disposition of the armament, configuration of the shore line and the topographic and hydrographic features, as affecting the number, location and employment of searchlights. 16. Centralization and decentralization of searchlight command. 17. The influence of fleet formations, lines of bearing and fort configurations on the employment of searchlights in various defensive areas. Many of the former basic principles and doctrines regarding the number, location and tactical employment of searchlights in coast defense operations have undergone marked revision and in some instances complete reversion. This is due largely to the introduction of new fire tactics, to the development of new fire control apparatus and to the necessity of rehabilitating and extending the fire control system itself. The effect of these developments is witnessed mainly in the modern doctrine of the centralization of searchlight command and in the restrictions placed upon the tactical employment of searchlights, as compared with their rather decentralized and promiscuous use in former times. Upon analyzing carefully and thoroughly the results and effects of the foregoing researches and developments, the necessity for remoulding the entire fabric of the previously existing searchlight organization becomes immediately and forcibly apparent. DESIRABLE CHARACTERISTICS OF SEARCHLIGHTS The coast defense searchlights normally employed against naval targets should possess the following general characteristics: 1. The light should give the maximum illumination at the maximum range. The minimum atmospheric absorption occurs between wave lengths .502 μ (micron) and .592 μ which is the range of green and yellow of the spectrum. Outside of these limits the absorption is very great. In the beam immediately outside of the front door, the intensity between the wave length limits .502 μ and .592 μ is about 72% of the total beam intensity, whereas after passing through the atmosphere, about 92% of the target intensity is between these limits. It would therefore seem advisable to cut out all rays below wave length .502 μ and all above .592 μ, thus transmitting only the highly efficient light. Such procedure would eliminate the reflected blue which causes so much trouble to the observer in sighting on the target, without reducing the actual range intensity of the beam. The blue rays reflected by the atmosphere produce a blanket of light to which the retina of the eye is fairly susceptible, thus reducing the contrast of the illuminated |