The temporary studding could then be removed, leaving the room clear, only about 2 inches from each side of the room being taken up with the waterproofing. Where "Paroid" was used as a waterproof layer the lining was held in place by means of bolts set in the walls and ceiling. Holes were drilled in about 6 inches, bolts set and grouted in place. Woons 2 by 4 inches were then fastened to the concrete by means o polts. The strips which were fastened to the top of the room ha i thickness of 2 inches at the center and a slope of 1 inch to the 100t toward the sides of the room. The "Paroid" paper was tacked onto the strips in the same manner as shingles are put on, so that there were at least two thicknesses of paper everywhere. Then tongued and grooved pine, cedar, or California redwood was fastened to the strips over the copper, the wooden ceiling supporting and holding in place the "Paroid" paper. Where a combination of the two methods was used the ceiling was worked into place in the same manner as described above where all copper was used. The plank for the entire side of the room was placed in an inclined position, the foot being at the place it was to occupy when finally fitted. The "Paroid" paper was then shingled onto the outside of the planking, the planking tipped up into its place as a whole, and joists nailed lengthwise of the room to support the ceiling in the same manner as where copper was used on the outside. In both methods where copper was used the planking was 2 inches thick. Where the "Paroid was used the tongued and grooved ceiling was the regular seven-eighths-inch thickness.

It was originally intended to line the inside of the sheathing with nonconducting material and one magazine was lined with magnesia lumber, one with "Transite," which is a material similar to the magnesia lumber, and a third with asbestos millboard. As this work was not completed until late in the spring, and up to that time the results as far as could be observed were quite satisfactory with the wood lining alone, and as the cost of the nonconducting lining was considerable, this lining was omitted from the other magazines.

An experiment was also tried with lining one magazine in which there was no percolation with sheet cork to prevent condensation. In this case the cork was stuck directly to the concrete. It was done under informal agreement with the company that sold the cork, the agreement containing a guaranty that the cork should be fastened to the wall satisfactorily and any that came off within one year was to be replaced by the company without cost to the United States.

In some of the new works which have been built during the past two years the magazines have been lined with a special porous brick, known as "Shawnee" brick, and in another case a battery has been lined throughout with hollow tile of special form.

Observations have been made from time to time throughout the summer of the results obtained by the work above described. In all cases where the copper was used percolation has been absolutely prevented. In two or three cases in which the "Paroid" paper was used it has evidently become punctured and small leaks have developed. These leaks, however, are hardly noticeable. Where the magazines have been kept tightly closed no condensation has been observed, but where the magazine has been opened irregularly or left open all of the time, as has been the case in some of them, there has been considerable condensation upon the wooden linings.

During the month of July, 1903, the weather has been at times extremely hot and the relative humidity has been very high. Inspections have been made particularly to observe the results of the linings, and the results in detail are as follows:

SITE NO. 1.

Inspection made July 6, 1903. The magazines in these emplacements have copper on the ceiling and "Paroid" on the walls.

Magazine No. 1.-No dampness in this room, but there was evidence that water had at some time come in under the lining of the walls. There was no evidence of any leak of walls or ceiling. The walls and ceiling felt dry. The door was closed and locked. The adjacent rooms were damp with water on the floors and condensation on the walls.

Magazines Nos. 2 and 3.-The magazines felt cool and damp. Walls and ceilings damp. A film of water covered more than one-half of the floor surface. No evidence of leakage in the walls and ceilings. Water evidently came in under the side lining. Doors were closed. Adjacent rooms were damp, with more or less water on the floors.

SITE NO. 2.

Inspection made July 6, 1903. Magazines have copper on the ceiling and "Paroid" paper on the walls.

Magazine No. 1.-The room was cool and damp. A film of water covered the whole floor surface. The ceiling and walls were damp. The door of the magazine was open, and it was reported that it had been kept open. Adjacent rooms were damp.

Magazine No. 2.-Magazine was dry. The ceiling and walls felt dry and warm. There was no evidence of any water in the room or having been in the room. The doors of the magazine were closed and had been kept closed. There was a quantity of powder stored in the room. The adjacent rooms were cool and damp.

SITE NO. 3.

Inspection made July 10, 1903.

Magazine No. 1.-Lining of 16-ounce copper held in place by planking, a floor of hard pine, two thicknesses, seven-eighths inch each, with an asbestos millboard layer between the two thicknesses. Walls and ceiling of room dripping with condensation. Door of magazine and outside doors of emplacements open. Rooms and galleries in the vicinity of the magazine were dripping with condensation. Water was standing in shallow pools on the floors.

Magazine No. 2.-Lining and floor the same as magazine No. 1, with the addition of a lining of magnesia lumber on walls and ceiling inside. of the planking. No condensation was visible in this room, except on the electric-light fittings. The door of the magazine was open, the outside door closed. Rooms and passages in the vicinity of the magazine dripping with condensation and floors very wet.

Magazine No. 3.-Lining and floor the same as No. 2, except that the "Transite" was used in place of magnesia lumber for the inside lining. The door of the magazine was closed; outside doors closed. This room

was perfectly dry. It had not been used by the artillery, and cement. for certain work in progress by the Engineer Department in the vicinity of the battery had been stored in the magazine for some time. Cobwebs in various parts of the room were plainly marked by cement dust which had settled on them. There was no condensation visible anywhere and no signs of there having been any at any time during the summer.

Magazine No. 4.-Lining and floor the same as No. 3, except that asbestos millboard was used in place of the "Transite" for the inside lining. The millboard felt damp and had swollen some, indicating that it had absorbed moisture, but there was no moisture standing anywhere in the room, except a little condensation on the electric-light fittings. Door of the magazine was closed, outside doors in the vicinity closed. Rooms and passages in the vicinity dripping with condensation.

Magazine in single 10-inch emplacement.-Lining of "Paroid" paper held in place by planking. In this magazine the "Paroid" paper was applied in the same manner as the copper in the other magazines, not as the "Paroid" paper was in the other magazines as described in the general statement above. The magazine was dripping with condensation and the planking appeared discolored and swollen from the effects of the water condensed upon it. Condensation was much worse in this magazine than in any other lined magazine. It is believed that this is partly due to the fact that this magazine is surrounded by a heavier mass of concrete than any other. The outside door of the passage leading to the magazine was closed, but the door to the magazine was open. All of the rooms and passages in the vicinity of the magazine were dripping with condensation, and the floors were covered with water, which stood in shallow pools.

At the time the inspection was made at this fort the thermometer was in the vicinity of 95°. A tremendous difference in temperature was noticed in passing from the outer air into the magazines, especially into that in the single 10-inch emplacement. It felt as though there was at least 40 or 50° difference in temperature between the outside air and the air in this battery. An inspection of the magazines at this fort was made again on July 30, 1903. On the latter date the temper ature was not quite as high as it was at the date of the first inspection and the amount of condensation was not quite as great, but the general conditions were practically the same as reported above, only in a lesser degree.

SITE NO. 4.

Inspection made July 30, 1903. All of the magazines in these. emplacements are lined with copper, held in place with planking, and have double-thickness wood floors, but have no lining inside of the planking.

Magazine No. 1.-The walls and ceiling felt cool and more or less. damp, and there was a little condensation noticeable, but not much. The door of this magazine has been kept closed throughout the summer, but the outside door of the passage has, as a rule, been left open. The rooms and passages in the vicinity of this magazine were dripping with condensation and percolation.

Magazine No. 2.-The ceiling and walls of this room were gener

ally fairly dry, but a streak of condensation on the ceiling the width of the door extended from the door across the length of the room and part way down the end wall. A close examination indicated that there was an opening about one-half inch wide between the door and the lintel, and apparently the warm air from the outside passed over the door, crossed the room, passed down the end of the room, and crossed the floor out under the door. Moisture was deposited from this warm current of air as it passed along the ceiling until it reached the wall at the end of the magazine opposite the door, by which time the moisture had been nearly all extracted from it. The condensation on the end wall gradually decreased from the top until near the floor it disappeared. In the magazine were a number of charges of powder in metal cases. Those cases which were piled immediately in front of the door under the damp streak on the ceiling were covered with condensation, while on those that were piled up at one side of the room no condensation was visible. The door of this magazine has been kept closed, but the outside doors have been generally left open. Rooms and passages in the vicinity of this magazine were dripping with condensation and percolation.

Magazine No. 3.-This magazine was warm and dry, and the plank lining appeared bright and without the slightest sign of discoloration, indicating that there has been no condensation in the room at any time during the summer. The door of this magazine has been kept closed. In the passageway in its vicinity was stored a miscellaneous assortment of paint, brushes, etc., belonging to the artillery, and all the doors in the vicinity had been kept closed and locked at all times during the summer. There was some condensation in the rooms and passages in the vicinity of the magazine, but not nearly to the same extent as in the others in this battery.

Magazine No. 4.-Magazine felt cool, but there was no condensation visible on the walls or ceiling, but there was a little discoloration of the planking, indicating that there had been some condensation. During the short time that the magazine was opened for the inspection condensation began to appear upon the electric-light fittings, where there was none when the magazine was first entered. The door of this magazine has been kept closed, but the outer doors have been part of the time opened and part of the time closed.

Magazine No. 5.-The conditions, here were practically the same as in magazine No. 4. Condensation was visible on the knots, and pitchy, hard places on the planking.

SITE NO. 5.

Inspection made July 10, 1903. One magazine in the old mortar battery lined with "Paroid" paper held in place with tongued and grooved sheathing. No wooden floor was laid in this magazine. Condensation appeared in spots, but was not very heavy. The sheathing had swollen in some places, indicating that it had absorbed considerable water. The door of the magazine was closed at the time of the inspection, but had been left open a considerable part of the time during the summer. The passageways in the vicinity of the magazine were open to the weather, being without doors, and these were dripping with

condensation.

SITE NO. 6.

Inspection made July 30, 1903. Two magazines lined with "Paroid" paper, tongued and grooved sheathing, with double-thickness wooden floors. Magazines were fairly dry. Evidences of slight condensation were visible. The floors had noticeably swollen. By lifting up a trap left in floor for the purpose of getting at the drains considerable water could be seen under one of the floors running into the drain, indicating percolation through the concrete on to the waterproof layer. In the other magazine no water was visible under the floor. The doors of the magazines were closed and locked. The doors of the outside rooms and passages were closed. Considerable condensation in the outside rooms and passages.

SITE NO. 7.

Inspection made August 5, 1903. Three magazines lined with "Paroid" paper, tongued and grooved sheathing, and double thickness wooden floors. The sheathing in two of the magazines is hard pine and in the third of cedar. Other conditions are identical.

In

In the magazines lined with hard pine the lining was covered with mold, indicating condensation. In the magazine lined with cedar the lining was as bright as when first put in, showing that there had been no condensation in this magazine at any time during the summer. this magazine the door frames were of hard pine, and these were covered with mold the same as the lining in the other two magazines. The doors of the magazines were closed. The outside doors were closed at time of inspection, but not locked.

SITE NO. 8.

Inspection made August 4, 1903. One magazine lined with sheet cork stuck directly to the wall. Considerable of the cork lining has come off and the company is taking steps to replace it. The cork was stuck to the walls with a special preparation of asphaltum. That which has come off appears as if the asphaltum was allowed to cool before the cork was firmly in place, but sheets of cork are now coming off which two months ago were apparently well fastened. There was no percolation in this battery. The cork lining was covered with condensation, was moldy, and much discolored. The door of the magazine was open, outside passage doors closed. Other rooms and passages in the vicinity of the magazine were covered with condensation. In another magazine in this same battery the conditions were identical with the one which was lined with cork except that there was no lining in it. The door of this magazine has been kept closed and locked all summer, probably not having been opened at all before the inspection was made. This magazine was perfectly dry and there were no evidences of condensation having taken place in it at any time during the summer. The gallery immediately outside of the door of this magazine was quite wet with condensation, but the balance of the rooms and passages of this emplacement were dry.

SITE NO. 9.

The emplacements at this locality are lined throughout with a special form of hollow book tile. The floors of the rooms slope from the center to the sides, and around the sides of every room are gutters

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