The first column gives the name of the shaft and the months.
The second, the dates when the shafts were commenced.

The third gives the monthly progress in sinking the shaft, and the total depth of shaft, including sump.

The fourth, the method of drilling and loosening the material of the shaft.

The fifth, the explosive used in the shaft.

The sixth gives the number of cubic yards of earth and rock removed from each shaft and included in the estimates for payment.

The seventh gives the relative amount of timbering in each shaft. In the West shaft the timbers are of 8 by 8 inch pine, with corner-braces and straining-beams 6 by 8 inches. Fourteen of these sets are placed 3 feet apart, and 6 sets near the bottom are 5 feet apart. The lagging and hangers are of 2-inch pine. At Foundry Branch, Rock Creek, and Champlain Avenue shafts the timbers are 8 by 8 inch pine, with a crossbrace dividing the 8 by 14 foot shaft into two compartments. These timbers are placed 3 to 4 feet apart. The upper timbers in these shafts are 10 by 12 inches, and in the Champlain Avenue shaft there are some of them 10 by 10 inches. The East shaft is timbered with frames and lagging, but in a much more substantial manner than any other of the shafts. The frames are all strengthened by diagonal cornerbraces and straining-beams, and 2-inch lagging is used. Commencing at the top, three sets of 12 by 12 inch timber were put in, spaced 4 feet from top to top; then fourteen sets of 10 by 12 inch, spaced 3 feet and 4 inches from top to top; then fiftysix sets of close curbing of 10 by 10 inch stuff; then three sets of 10 by 10 inches, about 1 foot apart, which took the shaft down to the rock and completed the timbering, except the temporary sets put in from time to time to furnish a platform for the pump.

The eighth column gives the size of the shafts inside the timbering. The east shaft was given a large cross-section, in order to allow the sheathing plan to pass inside the top timbering and outside that lower down, in passing through the bad stratum of quicksand known to exist about 40 feet down.

The ninth column gives the number of holes drilled in sinking the shaft.
The tenth, the number of pounds of powder used.

The eleventh, the number of days' labor expended.

The twelfth gives the character of the material passed through. The east shaft passes through a considerable depth of varied deposits, and I give here with the general character of these deposits, as observed and reported upon by Prof. T. Robinson, of Howard University, who has taken a great interest in the work.

NOTES OF STRATA AT THE EAST OR HOWARD UNIVERSITY SHAFT.

Beginning at about 131.5 feet above datum, the shaft was sunk first through about 2.5 feet of coarse, clean sand; then through about 32.5 feet of red clay, mottled with blue and white; then about 5 feet of clayey sand; then through about 6 feet of sandy clay, running into clear sand; 2 feet of sandy mud, containing much lignite; 6 feet of sand, containing nodules of sandstone, sand cemented with ferrous sulphide, pockets of clay, and scattered lignite; 9 feet of sand, fine, clean in spots, otherwise mixed with clay; 6 feet of fine sand mixed with kaolin, very wet (held water well and was a regular mortar-bed to work); 5-foot layer of ferruginous conglomerate; 9 feet of blue-gray clay, hard, compact, with a very unctuous feel; 9 feet sand mixed with clay of various colors, another mortar-bed for work (the last 3 feet of this was nearly pure sand, running at the bottom into a thin layer of ferruginous sandstone); 5 feet of clay, dark, hard, with greasy feel; 3.5 feet sandy sediment, running into pure white sand; 2.5 feet dark green sand, containing pebbles and lignite; 1.5 or 2 feet of fine sand light green in color. At about 103 feet down was struck a chloritic rock of the hornblende series, greasy to the feel, and very soft for about 2 feet down. From that point the rock was harder in proportion to the depth until it had been penetrated about 15 feet; since then there has been no great change in hardness. In fact, the last 20 feet of the shaft shows no change in this respect at all. The East shaft is still unfinished on June 30, 18-4.

The completion of the shafts was much delayed, owing to the failure of the contractors to get their compressed-air plant at work until a late date. All the shafts were entirely sunk by hand-power except the East shaft, where compressed air has been at work since May 26.

I also give herewith a table showing the progress of the tunnel and other data connected with the tunnel work.

The first column gives the shafts from which the drifts are started and the months of operation thereon.

The second gives the date of commencement of the drifts.

The third gives the depths below the top of the shafts to the top and bottom of tunnel.

The fourth gives the progress in linear feet for each month and the total progress up to the 30th of June. The greatest progress in any one month was 142 feet and 8 inches, in the west heading of the Rock Creek shaft tunnel.

The fifth gives the method of drilling, whether by hand or power drills.

The sixth gives the date of introduction of the power drills actuated from the central station compressing plant. The Ingersoll Drill Company who furnished the plant to the contractors failed signally in furnishing it at the time agreed and thus delayed the work very much.

The seventh gives the explosive used. In general, Atlantic giant powder number two has been used. Number one and number two extra are used where the rock is

hard and tight.

The eighth gives the number of holes drilled in each heading in each month as reported by inspectors.

The ninth gives the description of holes; these are generally started with a 24-inch drill, which is gradually reduced as the rock is penetrated, in order that the drills may chamber freely. The depth varies, but is usually about 5 or 6 feet.

The tenth gives the number of cubic yards of rock removed from each drift during each month, according to the estimates for payment, which includes only that within the least limiting cross-section of the tunnel, i. e., 77 square feet.

The eleventh gives the air-pressure at the power drills. At the central air compressor the gauge generally stands at from 65 to 80 pounds. The measurement given in this column is not at the drills, but at the shaft engine-house where the compressed air is used to run the hoisting engines.

The twelfth gives the approximate amount of powder used.

The thirteenth gives the number of days' labor expended, including foremen, engineers, blacksmiths, laborers, &c.

The fourteenth gives briefly the character of the material passed through. The rock in Foundry Branch and Rock Creek drifts is hard and compact gneiss, with now and then a seam of rotten rock a few inches in thickness. The hardness is very variable from almost pure quartz down. The dip of the rock is also very variable; it dips in every direction.

TUNNEL SURVEYS.

After it was decided to adopt the tunnel project and carry it in a straight line between the two reservoirs, three preliminary lines were run, and the line of the tunnel approximately determined. In the location a great many obstacles were met with, such as houses, trees, growing crops, &., necessitating many offsets and triangulations, thus increasing the labor of the survey and rendering the result uncertain.

To overcome the obstacles of the surface surveys, Capt. R. L. Hoxie designed two towers, by which sights could be made nearly the entire length of the line. For this purpose a tower was erected on the hill about 400 feet east of the distributing reservoir, and upon the third surface line surveyed. This tower was 11 feet 2 inches square at the base, 10 inches square at the top, and 110 feet.high, and had a 20-foot mast carrying a 10-inch tin ball on top. When this tower was completed a platform was placed on the roof of Miner Hall, one of the Howard University buildings, about 500 feet west of the trial shaft. The transit was set up on this platform and brought exactly in line between the mast of the west tower and the center of the trial shaft, and points were established on the roof of the hall, the hill east of the new reservoir, and the ground west of Miner Hall.

In the mean time an observation tower was erected. This was a double tower, or rather two distinct towers, one inside the other, each 66 feet high; on the outer one was a platform for the observer, while the inner one carried the transit, thus avoiding any disturbance of the instrument by the movements of the observers. The outer tower was 11 feet 2 inches square at the base, and 4 feet 11 inches square on top. The inner one was 7 feet square at the base, and 10 inches square on top. This tower was first erected on the hill about 200 feet east of Foundry Branch shaft. From this position of the tower a point was carefully established on each side of that shaft and a number between the tower and Georgetown. Then the tower was removed and set up midway between Rock Creek shaft and Champlain Avenue shaft. From this position of the tower a point was established on the east slope of the hill west of Rock Creek, and two between the creek and tower. The work had not been completed at this place when this tower was blown down during a wind storm, and completely demolished, as was the west tower a few days later.

In the work on the tower, the transit was removed from its tripod and placed on the small platform of the inner tower, and moved at right angles to the line till it