ing that the field-stone of eastern Massachusetts, whose exterior appearance resembles our field stone somewhat, cannot be worked at all as we work our field stone, with hammers and fire, I am under that impression.

son.

PROF. PETTEE: I do not know any reason why they should not. I was born in eastern Massachusetts; my father had a farm there, a few miles out from Boston. I was the youngest The work was all done before I was born, but, as he was troubled with a large number of field-stone boulders, he built with them what was known throughout the neighborhood as "the stone barn," 100x40, and he used many large stones in the foundation, which was about eight feet thick. That is a standing example of field-stone in a building in the neighborhood of Boston.

PRESIDENT DAVIS: What I refer to is the flat surface. We take our 30-pound hammers for pounding, and sometimes we use fire to get a crack started. My father, who has had plenty of experience, when I told him of the manner in which we worked our field stones in this country, laughed at the idea that anything of the kind could be done with Massachusetts field stone.

PROF. PETTEE: I know we used to blast them, in Massachusetts. Those of my friends who have visited me at Ann Arbor have expressed considerable surprise at our method of treating these stones.

PRESIDENT DAVIS: I was questioning whether my father's limited experience, was really a representative fact or not, that the eastern stone could not be worked as we work our Michigan field stone. I thought there was a suggestion in it for us.

PROF. GREENE: Michigan stones are granite I believe. I know when I was in Maine they would break them up with a hammer.

HYDROGRAPHIC SURVEYING.

JOHN HARRIS FORSTER.

Surveying on land is, of course, a familiar operation to most of you. All are not as familiar with hydrography.

The surveys of sea coasts, of the great lakes and rivers of this continent, have been conducted by the government, thereby debarring private enterprise and affording no opportunity for practice to the majority of civil engineers and surveyors. The writer having had some experience in this work, has been encouraged by your worthy secretary to submit some practical points for your consideration. He will not undertake to unfold the whole scheme of hydrographic surveying so ably carried out in the survey of the northwestern lakes, for instance, by the government of the United States through its war department. In brief, he will attempt only a few disjointed sketches, hoping thereby to give you, who may be interested in the subject, some idea of the work.

The survey of the northern lakes was not limited to mere off-shore soundings, but embraced shore-line surveys and topography, and a limited reconnaissance of the interior; also, deep-sea soundings, primary and main triangulation, reaching across rivers, bays, and the wide lake itself. All rivers of commercial importance, present or future, emptying into the lakes, were accurately surveyed as far up from their mouth as the case required. Especial attention was given to the mouths of rivers where sand bars and clay banks occur, choking the free outflow of the stream. The soundings at such points were minute and comprehensive, covering the whole delta. The finished chart would show a complete picture of the bottom, with its shoals, bars and tortuous natural channels. The material composing the bottom, ascertained by the lead or by borings, whether of sand, clay, gravel, boulders, hard pan or solid rock, was carefully noted. A plan was thus given which would be of great service to those who should follow in the work of river and harbor improvements.

The survey of the great lakes extended through many years, four or five decades, and was completed only a few years ago. It had for its superintendents, from time to time, army engineers who, later on, became distinguished generals in the war on the union. Captain Meade was one of the most brilliant and accomplished of these superintendents. Serving under him were many civil engineers. He called them his "boys." The "boys" loved and respected their commandant. Returning from the victorious field of Gettysburg, after receiving an ovation in Detroit, he sought out his "boys" and spent a delightful evening with them, recounting not the deeds of ensanguined Gettysburg, but the old camp stories of the lake

survey.

The survey was well organized and well equipped. It consisted of several shore parties or camps. An iron steamer was attached. Its duty was to place the shore parties in the field in the spring, visit them once a month with the mails and provisions, and for inspection. The steamer also made the deepsea soundings, and conveyed the officers conducting the main triangulations to their several stations, miles apart.

Belonging to the survey were several independent field parties. They were widely posted along the chain of lakes.

There were about twenty-five men in each party; four officers, one foreman, one cook; the rest were boatmen, chainmen and axmen. They lived in tents. There were usually two or three cutter-built, six-oared boats and one bateau, which last was used in transporting provisions and camp equipage belonging to the party. In camping the places preferably chosen were sheltered bays or mouths of streams, but sometimes the open roadstead had to suffice for the anchored boats. During heavy storms, in such case, the flotilla was hauled out on the beach. The tents were usually pitched on high, dry land, under the pine trees, near the shore, with a water view and a broad sand beach for a promenade. Thus situated, the camp, with its white tents placed in order, with underbrush cleared off, presented to the view a cozy hamlet in the wilderness. For many years the camps were isolated. There were no settlements, no human habitations, except the Indian wigwam, to be seen. During the entire season, it may be, the party saw no

one in civilized garb, except the men on the survey steamer. Long stretches of the lake country was an unbroken wilderness. Dropped some still afternoon by the steamer on a wild, untracked shore, the surveying party was left to its own resources. Before the retiring steamer was out of sight the camp was pitched, the stars and stripes flung to the breeze, the cook busy over his stove and the camp fires blazed cheerily. Our surveyors were "at home" to all callers, including the impudent mosquitoes.

Camp comfortably established, on the morrow at 5 a. m., real work began. The men were classified and assigned to the command of the several officers. Thus there were two or three sub-parties in camp. The senior officer commanded the whole. Surveying instruments were brought out and adjusted, and sounding lines compared. One gang of men was set to work making buoys, another was sent to clear out lines along shore, erect sounding stations, instrument stations, as well as secondary triangulation stations. All were busy as bees. On the first clear night an observation was taken to determine the true meridian and variation of the magnetic needle. Every ten miles, as the work progressed, new observations were made for the same purpose. The shore line was run with a theodolite. The start at the initial point was from the established meridian. The needle was never used, except to get the variation.

HOW TO MAKE BUOYS.

The buoy is an important factor in hydrography. On the survey a good practical buoy was gradually evolved. Dry cedar trees were procured from the swamps. This wood is light, buoyant and not easily water-soaked. A tree about one foot in diameter was best. It was cut into pieces, two and onehalf to three feet long. One end was shaved off like a truncated cone and a two-inch auger hole bored into it. Into this hole a spruce pole about two feet long, two inches thick, with a wedged end, was driven firmly. A hole was bored through the lower end of this stick large enough to let the anchor rope pass through and tie. The top of the buoy, sawed off square, was also bored and a light spruce staff, five or six

feet long, inserted and securely fastened. On this staff a small flag, one foot square, was tacked.

A large number of buoys and flags were required. The flags were made of cotton; white, red and black were the colors preferred. Practice determined that these colors were best for use, under all circumstances. This was important; it is often difficult and perplexing to make out a buoy on the water.

These primary colors, so to speak, admitted of many combinations. For example: No. 1 might be solid white; No. 2, red; No. 3, black; No. 4, white and black (horizontal bars); No. 5, red and white; No. 6, red and black, and so on. When these combinations were exhausted the colors were placed vertically, with the same number of variations as before. If more flags were required, diagonal bands were used. These flags were all made in camp, from bolts of cotton cloth.

Each book of soundings and each book of shore-line work, had these buoy flags recorded and painted in them and duly numbered, in order that the observer, on land or water, might have a ready reference. With naked eye, or telescope, the observer could pick up one of the many fluttering flags in the offing, when, by referring to his book, he would find its name. In sounding, before the boat leaves the shore, the officer in charge must ascertain definitely which flag or buoy he is to steer for. There must be no doubt about the buoy; any confusion of flags would cause a loss of a line and a breaking up of the plan for the day.

The buoy ropes used were of manilla, one inch in diameter. The anchors, carefully selected stones found on the beaches and weighing from 10 to 50 pounds. A coil of rope was carried in the boat.

In placing the buoys we ran out from the shore, sounding the while, until we found one fathom of water. Upon the six-foot curve, technically so-called, the first buoy was dropped. The line was extended up and down the coast several miles, but within a convenient row to camp. These buoys in line were several minutes apart or from 500 to 1,000 feet, according to circumstances. The character of the bottom determined how near or far apart buoys should be placed. The engineer was called upon to exercise his best judgment in the matter.