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The second camp way pitched on Davignons Point, and was occupied until September 29, having moved camp with the tug Myra. An area of about 9 square miles was surveyed from this camp, including the western portion of Sault Ste. Marie, Ontario, the Canadian canal grounds, Swedish settlement, and the country about 4 miles west of the town. A line of levels was also carried from a bench mark near the Canadian Lock, previously established, to a bench mark on Dick Moores Point.

The third camp was located between the Big and Little Carp rivers, about one-half mile from shore. Moving from Davignons Point was done by team and wagon. The area covered from here was about 11 square miles.

More work was done from this camp than would ordinarily have been advisable, but for several reasons it was considered best to survey the Point aux Pins region from here, and not to occupy this locality with a camp.

The more important reasons leading to this conclusion may be thus stated: According to orders, the survey was to extend north as far as the bluffs, and this necessitated an inland camp. As there is only one road, which is very bad in places, leading from Point aux Pins to the north, and as the bulk of the work was done at some distance inland, it was thought best to complete the shore line and the lower portion of marshy country while being located at the Carp River camp, and then to move camp by wagon to the second line road, which was done October 23.

On October 9 and 10 I continued the levels from a bench mark on the base line road, previously established, to about one-half mile east of Gros Cap, at the Indian settlement.

The plane table being the only instrument available up to October 12, was used exclusively previous to this time. The weather was becoming very disagreeable, cold and rainy, so that the plane table was entirely abandoned as soon as a transit was placed at my disposal. Since October 12 the plane table was used only three days, during exceptionally good weather, on shore line work.

The camp No. 4, on the second line road, was occupied from October 23 to November 14. During this time the party lived in a vacant house which they had rented, in preference to camping in tents. The plan was a good one, as there was much rain. It kept the men in excellent health.

About 13 square miles were covered from this camp, completing the survey to South Gros Cap.

At this time continual snowstorms made the progress very slow, but the work was nevertheless continued to North Gros Cap, in compliance with the orders received. This necessitated moving camp to South Gros Cap on November 14, and working as the weather permitted.

The larger portion of my camp outfit was moved to Sault Ste. Marie, Mich., via Point aux Pins, in sleighs, and the party took possession of Assistant Engineer Haskell's camp, as Mr. Haskell was no longer in need of his outfit.

The continued snow made the traveling very slow on the Gros Cap ridge, and as the country is thickly wooded there was much cutting to do, so that this work, covering only about 2 square miles, was not completed until November 28.

Messrs. John Conrick and C. E. Thompson walked to Sault Ste. Marie, Mich., to report the completion of the work and that camp should be moved.

The first opportunity for the tug Myra to land at Gros Cap occurred on December 1, when the remainder of the party and the outfit were brought back to Sault Ste. Marie. The trip was very stormy, and one of the tents was blown overboard and could not be recovered.

The plotted and inked field sheets, numbered 1 to 5, together with notebooks comprising the records of the survey, were filed in the office at Sault Ste. Marie, Mich.

The party was discharged and I returned to Detroit in obedience to a written order from Col. O. M. Poe, reporting for duty in Detroit on December 3, 1893.

METHODS.

The plane table with stadia was used exclusively from August 14 to October 12, it being the only good instrument provided for this work. From October 12 to completion of the survey, November 29, a transit and stadia was used, with the exception of three days. This transit had been used by Assistant Engineer E. E. Haskell on the triangulation work, and became available just at the time the cold and wet fall weather set in, and the plane table would necessarily have been discarded.

While working with the plane table the various duties were distributed among the members of the party as follows: The chief of party did the field plotting and took the station settings, directed the rodmen, and planned the general course of the work, besides looking up any doubtful matters. The recorder took the instrument pointings for side shots, recording all readings in his notebook, while the chief would plot the readings and number the points as recorded, so that it was possible to identify each plotted point in the notes.

Three rodmen did the regular rodding work and the fourth carried the plane table. Of the three regular rodmen the best man was selected as head rodman, the second best as side rodman, and the less competent as rear rodman. The man showing the least aptness was detailed to carry the instruments.

The field platting was done in pencil and the sheets were executed in ink during rainy weather and evenings. These field sheets formed a complete record of the work, showing all fences, boundaries, shore line, waterways, dwellings, and all other topographical features of the ground, including 20-foot contour lines. The notes, which contained only the data for finding the elevations of the contour points, were worked up at night by the recorder, and the elevations were then written on the field sheet. When sufficient area had been covered in this manner the contours were drawn. This method was found to be the most expedient when taking 20-foot contours on a scale of 1:10000.

It might be mentioned, however, that on very detailed work in mountainous country, where, say, 5-foot contours may be required and the work is platted on a large scale, it would be best to change the above programme and compute the elevations with a slide rule while on the ground and draw the contours before leaving a station. This method is necessarily much slower, and though it was first adopted, it was soon abandoned and the notes were worked up in camp.

A more detailed account of the manner of doing plane-table work may not be out of place, and may be useful in future work on St. Mary's River.

The plane table was used much in the same manner ay a transit in doing stadia work. A field sheet was commencod by locating upon it one of the lines of the tertiary triangulation system, for example, the course AA-AB, having previously decided upon the area of country to be covered by such a sheet, so that the line could be correctly drawn. This was usually done in camp. One of these stations, as A A, was then occupied, orienting the table on the line A-B, and shots drawn to all visible stations and prominent objects. The other station A B was then occupied with the instrument oriented back on the line A-B, as before, and shots drawn to the same points as from the A A. This then located all the objects sighted, by intersection, assuming that the line A-B was correctly measured off on the field sheet. Such preliminary preparation forms a basis for checking all subsequent work on the shoet, and also affords means to locate the position of the instrument when placed at any point in the field.

The filling in of details on a sheet thus prepared was done precisely as it would have been with the transit and stadia, only that each point was platted immediately in the field and all details were drawn before leaving the ground. It was inade à practice to run polygonal lines between the points previously determined, thus checking both the original points, as determined by intersection, as also the polygon. In this way it was scarcely possible to introduce any error in the work.

The transit and stadia was used in the same manner as was done on the Mississippi River Commission survey, and the work was platted in camp and inked in the same manner as the plane-table sheets.

RECOMMENDATION REGARDING METHODS TO BE FOLLOWED IN FUTURE WORK. The comparative utility of the plane table and transit depends entirely upon the character of the topography and the weather.

The plane table can be advantageously used only in open country and during dry weather. Strong wind is a hindrance. The transit can be used in any country and in any weather in which men can work.

In open country, where there is much detailed topographical work, I should say that a party could cover about the same area, in the same time, with either instrument; but the plane-table work would be platted, while the transit work would not.

In wooded country, or such localities where there would be comparatively few side shots, the transit has decided advantages, it being a much lighter instrument. especially adapted to quick settings, and requiring no such care as is necessary to prevent the field sheet from becoming soiled or injured.

As may be supposed, my party was considerably delayed between August 14 and October 12, the work being confined to weather which would not injure the planetable sheets. I have estimated a loss of about twelve days between the dates just mentioned, on which transit work could have been done perfectly well; but having no other instrument, this time could not be utilized for field work, and the men were employed in the best possible manner preparing for future work. This time, therefore, was not an actual loss; yet the field work, which represented the real progress, was delayed.

This was the best part of the season, an l between October 12 and November 30, there were only fourteen days which would have permitted the use of a plane table, while with the transit only eight days were lost on account of severe rain and snow storms.

It would seem, then, that a party ought certainly to be equipped with a transit, and, if practicable, to be provided with a plane table to be used when opportunities are offered.

I should also recommend, if new transits be purchased for future work, that these possess some of the features of the Buff & Berger plane table, that is, be provided with a telescope which can revolve on its optical axis, making the adjustment for collimation similar to that of a Y-level. The level should also be a detachable striding level as provided for the plane table. This will make the transit suitable even for running accurate levels.

The tangent screw for the horizontal movement of the plane table is a defective mechanism, for it produces a lost motion in the screw and the ball and socket joint. This movement should be carefully avoided in future instruments. The only perfect mechanism of this kind made up to this time is the movement which Messrs. Buff & Berger make for their transits.

It would be advantageous to have one or more of the stadia rods made to read 500 meters, instead of all to 400, as there is often great advantage in being able to read long station distances.

It might also be suggested that the rates of pay of the party be changed more in proportion to the duties imposed, and the following would seem a fair disposition to make:

Per month. Recorder.

$80 Head rodman

60 Two side rodmen

50 Rear rodman

$30 to 40 Cook.......

30 to 50 As the progress of the work is greatly dependent upon the efficiency of the head rodman and recorder, these men should be carefully selected and should possess a full knowledge of the work. The best men for this purpose are young engineer students.

A fair knowledge of drawing is almost indispensable to the recorder, especially while doing plane-table work, as he is called upon at times to take the place of the chief, or do independent work when both transit and plane table are being used simultaneously.

If future work is to be done on a larger scale than last summer's, it might be advisable to provide two recorders, both of whom should be capable of doing instrumental wor.. Such a party ought to be supplied with one rear and one head rodman in addition to the above personnel. Both instruments might then be employed in the field and each used to its best advantage.

STATISTICS.

Amount of work done.-In attempting to state the amount of work done the only data which conveys a reasonable impression is the area covered, yet this is very unsatisfactory, as the amount of work necessary to survey a square mile of country differs very widely. So, for instance, the vicinity of Sault Ste. Marie, Ontario, requires vastly more detailed work than does the open marsh meadow on Point aux Pins.

During the season's work an area of 40 square miles was surveyed, containing a developed length of shore l ne of 38.7 miles. Of this area 17 square miles were surveyed with the plane table in 35.5 working days, and 23 square miles with the transit and stadía in 29 working days, making a rate of 0.48 square mile per day with the plane table and 0.65 square mile per day with the transit.

The whole time spent in the field was 109 days, of which 35.5+ 29=64.5 days were spent in actual field work. The time lost to field work - 109—64.5=44.5 days, is accounted for as follows:

Days. Sundays ...

16 Moving camp

6 Loss by rain while working with the plane table

14.5 Loss by rain and snow storms while using the transit.

8 Total....

44.5 Cost of work. The following are the expenses incurred in equipping my party and surveying the above area on the Canadian shore of St. Marys River, between the Shingwauk Home and North Gros Cap, between the dates July 1 and December 1, 1893:

ENG 94 -215

Ins ruments

$305.00 Camp outfit

302.38 Provisions...

369.29 Labor, including chief of party.

1, 899.98 Sundry expenses for traveling, etc

85. 36 Total.....

2,962.01 of the amount thus expended the instruments and camp outfit are still available for future work. Assuming a depreciation in value of the instruments of 10 per cent and of the camp outfit of 50 per cent of the original cost, the following would represent the actual cost of the survey: Instruments, 10 per cent of $305.

$30.50 Camp outfit, 50 per cent of $302.38

151. 19 Provisions, labor, and sundry expenses.

2, 354.63 Total.....

2,536.32 This gives the average cost per square mile of survey, all expenses incidental to the work.

40 Very respectfully, your obedient servant,

DAVID MOLITOR,

Assistant Engineer. First Lieut. CHARLES S. Riché,

Corps of Engineers, T. S. A.

$2,536.32 – $63.41, including

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II.---REPORT OF MR. E. E, HASKELL, ASSISTANT ENGINEER.

UNITED STATES ENGINEER OFFICE,

Sault Ste. Marie, Mich., April 28, 1894. SIR: I have the honor to submit the following report upon the reduction of the observations of the line of precise levels run by Messrs. E. J. Thomas and A. O. Wheeler in June, 1892, between B. M. "A" on the canal lock of 1881. at Sault Ste. Mario, and the water gauge at Waiska Bay.

In my last annual report (p. 4359 of the Report of the Chief of Engineers, U. S. A., for 1893) I made the statement that the elevation of the zero of the water gauge at Waiska Bay should bo corrected by a minus 0.152 foot, the difference in the elevation of B. M."1" and B. M. "A." From the final computations of the levels it appears that Mr. Thomas must have had the elevation of B. M. “A” and called it B. M. "F," so that there is no correction to the elevation of the zero of the gauge at Waiska Bay as indicated in my report. B. M. "F"is the only one mentioned in the notes as the starting point for this line of levels, but the elevation of it or of the bench mark used does not appear, which accounts for my being led astray in my first interpretation of them.

In regard to the connection of this line of levels with the gauge at Waiska Bay we are dependent upon the statement made in the field report, which is undoubtedly correct, as to the elevation of its zero. In the notes there is no statement as to how the connection was made.

In connection with the reduction of the observations I haro determined the constants of the precise level, Kern No. 2, with which this line was run and these new values have been used in the computations. These values are given below:

Wire interval between extreme wires equals 1m.038 for a base of 100+f+c where f=0m 366 and c=0m 177. Hence d, the distance, equals 96m.34 8 + 0m 54 where s equals any intercept on the rod.

The value of one division of the level tube of the striding level was determined by means of a level trier, and found equal to 4".801.

The inequality of the collars was determined by the striding level with the result eye-end collar 0.53 of a division of the level tube, or 2.544 larger than object-end collar.

The observers were very careful indeed to make back and fore sights equal, so that in the whole line of 14 miles of double line run there is only two or three stretches where any corrections appear. From my computations the zero of the Waiska Bay gauge is 1.1497 meters=3.7720 feet below B. M.“A," agreeing closely with the value given in the field report of the work.

There were four P. B. M.'s determined, located at intervals along the line, and the elevation of these, together with the descriptions of them, are given below:

Elevation above mean sea level of B. M. “A” on northwest wide wall of canal lock of 1881=605.872 feet = 184.668 meters.

Elevation of P. B. M. No. 1 above samo reference=642.007 feet=195.682 meters. Elevation of P. B. M. No. 2 abovo ramo reference = 641.312 feet=195.470 meters. Elevation of P. B. M. No. 3 above same reference=670.321 feet = 204.312 meters. Elevation of P. B. M. No. 4 above same reference=648.027 feet = 197.517 meters. Elevation of the zero of the Waiska Bay gauge=002.099 feet = 183.518 meters.

DESCRIPTION OF DENCH MARKS.

"P. B. M. No. 1 is tho top of a copper bolt set in the top of a large bowlder. The bowlder is 12 feet west from the center line of the Duluth, South Shore and Atlantic Railroad, and about 200 yards north of the 3-mile post, and is marked with the letters U.S. B. M., cut into the surface on the cast side.

"P. B. M. No.2 is the top of a copper bolt in the center of a stone that is buried 4 feet deep. The stone is on the west sido of the Duluth, South Shore and Atlantic Railroad, 30 feet west from the center line of the track and 45 feet north of the 6mile post. A tamarac post, 6 inches in diameter, sets upon the stone, and projects about 16 inches above the surface of the ground.

"P. B. M.No.3 is on the west side of the Duluth, South Shore and Atlantic Railroad, 21.5 feet north from the 9-milo post, and 31 feet west from center of railroad track. It is the top of a copper bolt set in a square stone that is buried about 4 feet deep. A cedar post sets on the stone and projects 16 inches above surface of ground.

“P. B. M. No. 4 is the top of a copper bolt set in a stone that is about 18 inches square and buried 4 feet in the ground. The stone is 311 feet north from the center line of the Duluth, South Shore and Atlantic Railroad, and 192 feet west from the west end of the railroad bridgo across Waiska River, at Bay Mills station, almost due north from the frog on the branch line turning out to Waiska Bay. A cedar post 6 incles in diameter sets upon the stone and projects 2 feet above the ground. The letters U. S. B. M. are carved in the south side of the post.”

SLOPE OF THE RIVER.

The Bay Mills gauge was read daily between 8 and 8:30 a. m. from June 6 to Sep. tember 9, 1892, inclusive. The elevation of the mean reading from this series of observations, or the mean lake level for this period, eqnals 601.826 feet above mean sea level. The gauge at the head of the canal at Sault Ste. Marie is read daily at noon. The elevation of the mean reading for the period given above is 601.412 feet above mean sea level, making the slope of the river from the Bay Mills gauge to the head of the canal 0.414 feet, or 0.037 feet per mile, the distance between the two gauges being in the most direct line by the channel 11.3 miles. This determination of the slope for this reach is of course not as satisfactory as if the gauges had been read simultaneously, but can be considered a close approximation.

In view of the excellent opportunities offered at Point Iroquois Light-House for establishing a gauge and the possibility of having the light-keeper read it daily for the period of a year at least, I would respectfully recommend the continuing of this line of precise levels from P. B. M. No.4 to Point Iroquois Light-House. This distance is only 6} miles over a reasonably good road, representing not to exceed 4 days' work for the ordinary leveling party. The angle party of the primary triangulation could do this work at very small expense while they are occupying A Iroquois, which is in the vicinity. Very respectfully, your obedient servant,

E. E. HASKELL,

Assistant Engineer. First Lieut. CHARLES S. RICHÉ,

Corps of Engineers, U. S. Army.

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