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Sixth, the number of the teachers is so proportioned that there shall be at least one teacher for every four or five students.

Seventh. Very little or no instruction is given by lectures or by text-books, and no recitations are required. It is essentially a school for the application of principles already acquired. Lectures are given in order to sum up the results of the field work and to keep the work of the whole school before the mind of each student.

Eighth. All work of the students is so arranged as to be susceptible of being tested for accuracy by the students themselves, and the method found most suitable to be employed for this testing has been to so arrange the work that different parties of students may check each other, or the student checks himself by employing different methods for obtaining the same result. So far as possible, wherever the plotting is a check of the work, it is arranged that the plotting shall be done by other students than those who obtained the notes. These checks correspond with those existing in practice and seem to have furnished satisfactory tests.

Ninth. One of the most important features of this school is that all the work is made subservient to the one object of giving equal and adequate instruction to all members. No attempt is made to accomplish any definite amount of work beyond the direct usefulness of that work as a means for conveying practical knowledge to the mind and hand of the student. The question of economy of time is insisted upon from the beginning, but the sacrifice of uniform instruction for the completion of any certain area of work is absolutely avoided. The work, when finished, may be valuable and may be incorporated into other work of commercial value, but the desire to make the work for a specified purpose is studiously avoided. The fact that a student develops unusual facility in certain directions rather shortens than lengthens the portion of time for which he may be assigned to that particular task.

The work of the summer school of the Massachusetts Institute of Technology has been carried on during the last five years at several different localities. These changes have been made partly on account of the difficulty of finding an ideal location and partly because there are certain problems which are best illustrated by making a fresh reconnoissance the first step in the work. The school of 1888 was held at South Deerfield, Massachusetts; that of 1889 at Schoharie, New York; that of 1890 at South Deerfield again; that of 1891 and 1892 at Delaware Water Gap, Pennsylvania; that of the present year in the Adirondack region of New York, near Keeseville.

The attendance at these summer schools has never been large, as the requirements for admission have been adhered to strictly. The average number of students attending has been fifteen. This year there were twenty-five students.

The speaker then described the vacation work of the Massachusetts Institute Technology orally as follows:

He first described the hydraulic measurements. He had selected as an illustration their work of the

year 1892, at Delaware Water Gap, Pennsylvania. He showed wall diagrams illustrating the work. The discharge of a stream and of its two branches had been measured by two methods, floats and meters, and these were made to check each other. The local conditions at the several sites were also very different. In this way the student's work can be checked without any suggestion of attempted fraud on his part. The students took great interest in doing all their work with the greatest care.

The speaker then described the experimental geodètic work of the class. This consisted in the measurement of the base line and the horizontal and vertical angles in a small system of triangulation. This was a new country, visited by the students for the first time, and the problem of reconnoissance for points was an important one. It was a region particularly well situated for developing this portion of the work. In the first place, it was a valley surrounded with hills. The reconnoissance readily developed the fact that a large quadrilateral of very good shape could be obtained without much difficulty. The construction of a signal took about one hour and a half of the students' time and was a profitable lesson. The location of the base line was not ideal, but not very far from it. It was an important fact that the government coast survey had worked up into this region, and had established here one of their points. From the Coast Survey we obtained the latitude, longitude, and elevation of this point. The work, therefore, could all be referred for its geographical position and for its elevation to this point if it could be connected with this system of triangulation. That was done, and the latitude and longitude determined, so that the geographical positions of all these points could be worked out and the L. M. Z.'s determined.

The system pursued in this work had been strictly that of the coast survey observations. He referred to the measurement of the baseline as part of the geodetic work, and he did this not to show what amount of work was done, but rather to show what this field instruction might do in developing in the mind of the student a spirit of investigation. They had measured a base line each year of the five years of summer school work, with the steel tape. It is well known that measurements with the steel tape may be made with an accuracy of one in one million. So that with this simple apparatus they might be considered as doing something of a geodetic character. They had developed an apparatus for doing this work from year to year. The students had been sufficiently interested so that when suggestions were made to them in regard to the development of the work they had responded in such a way that he felt that they had developed an apparatus which for easy manipulation in the field, and for accuracy of results, compared very favorably with any that he had ever seen.

The tape was suspended above the ground. To find the length of the tape it is placed in the same position in which it is used in the field, over a space of known length. All that could be done in the summer school was simply to repeat measurements and see whether they agreed. The problem was to suspend the tape in line so that there would be as little friction as possible at the points of support, to stretch the tape with a uniform pull, and to determine the temperature of the tape. The last of these was the most difficult, and he could not say they had solved it. He would say in regard to the intermediate supports, it took a good deal of time to drive stakes and put in nails, and he did not see any necessity for it. They had a light line of poles which could easily be aligned accurately enough by the eye. Then on these posts they put hangers, which could be raised, and on these were placed hooks for supporting the tape. These formed the points of suspension, which were very quickly aligned by the eye, and were as firm as need be. The speaker here exhibited a stretching devise which he said had been devised by H. C. Bradley of the class of 1891. Speaking of the results obtained he said they had measured two lines by repetition, a mile in length, the variation between these measurements being only one part in one million. They had measured a line of a kilometer in length four times with a probable error of the mean of one part in one million five hundred thousand. The temperature question is a thing which has been difficult to contend with. They could only get the results referred to when, by using the thermometers, they can call the temperature of the air the temperature of the tape, and that can only be when there is a drizzling rain, or when the measurement is taken on a very cloudy day, or perhaps possibly at night, as Mr. R. S. Woodward of the coast survey had suggested. In the

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