After the report was made part of the public records, the development and adoption of a suitable disappearing gun carriage caused the substitution of open emplacements for the expensive turrets and armored casements, materially reducing the cost of installing the armament. The great advances in ordnance, increasing the power and range of the later guns, caused a diminution in the number and calibre of the pieces to be mounted, and this fact, combined with advances in the science of engineering, rendered unnecessary the construction of the expensive “floating batteries” designed by the Endicott Board for mounting guns to give sufficient fire for the defence of wide channels or for harbors where suitable foundations could not be secured on land. Furthermore, keeping pace with the gradual development and improvement in the engines and implements of war, fortified harbors are equipped with rapid-fire guns, and, to a certain extent, with power plants, searchlights, and a system of fire control and direction, now essential adjuncts of a complete system of defence, though not so considered by that board. While the details of the scheme of defence recommended by the Endicott Board have been departed from, in making provision for later developments of war material, the great value of its report lies in the fact that it sets forth a definite and intelligible plan or policy upon which the very important work of coast defence should proceed, and which is as applicable to-day as when formulated. The greater effective ranges possible with the later rifled cannon, the necessity of thoroughly covering with gun fire all available waters of approach, and the growth of seacoast towns beyond the limits of some of the military reservations, have combined to move defensive works more to the front, and many of the gun positions now occupied have been obtained from private ownership. The cost of such sites has been a large item in the present cost of fortifications, and this purchase of land was not included in its estimates by the Endicott Board. An examination of the report also discloses the fact that no estimates were submitted covering a supply of ammunition to be kept in reserve for the services of the guns that were recommended, due, perhaps, to the fact that a satisfactory powder to give the energy desired and a suitable projectile to accomplish the desired destruction of armor were still in experimental stages. These questions, however, are no longer in doubt, and Congress already has made provision for some of the ammunition needed.