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results referred to the best conditions had of course prevailed. The speaker referred to the base line work the past

One of their students was so deeply interested in this work that after taking a post graduate course at the Harvard University, he wished to come back to the summer school and try some experiments with the galvanometer for the purpose of finding the temperature of the tape by the variation of resistance. The results were hopeful. Some tables were shown which indicated that it could be done. Experiments which had been made since the summer school closed were still more encouraging, and he was in hopes that something might come of it.

In regard to the rapidity of the work, he found there was no difficulty whatever in taking a measurement of one hundred meters in fifteen minutes' time. This included the alignment of the points of support, the putting in of the stakes at either end, the leveling of the points of support and taking and recording the results of the measurement. This could be shortened by experienced observers, and the speaker believed these methods of measurement, involving an accuracy of one in five hundred thousand, could be used for the measurement of lines in the preliminary laying out of city lots. At least these methods had stimulated the students to original work in perfecting so simple a method of measuring to such extreme accuracy.

The speaker next referred to the topographical work proper. This is the work that he thoroughly believed needed continuous field practice in order to give ade

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quate instruction. The best instrument for topographical work had seemed to him to be the plane-table. There was a great difference of opinion on that point among civil engineers, but there was no difference of opinion on some of the government surveys as to how the work should be done. When they want topographers, they want men who can use the plane-table, so that if students fitted for topographers and geodesists, they must use the plane-table. He believed it to be impossible to give adequate instruction with the plane-table without using some particularly well adapted locality and carrying on the work day after day with the student. They do not spend more than a week's time on this subject with any one student, but a week of continuous work, it seemed to him, was necessary in order to give this proper instruction.

The speaker explained how a plane-table triangulation was first made, working from the measured base line, and the position and elevations of the triangulative stations fixed on the map. The elevations were obtained in such a way that they were not accepted until three different determinations check them. The great advantage of plane-table work was that a mistake could not be made. The student could not make a mistake and deceive his instructor. If a mistake has been made he cannot adjust the points and the work must be gone over the next day. After getting his framework, he determines the elevation of the table by sighting on three known points, and then he goes ahead. The ground is thoroughly covered, and a correct map is obtained. He felt certain of this because every time the table was put in position there was an opportunity to test every other point. By means of this instrument alone every man had to make a map of the area. So much for the matter of planetable work in the summer school.

Stadia work is taught also in connection with this, but as he could not test that work until it was plotted, they had to wait until the school had closed to get that time.

He spoke also of a portion of the work which consisted in the location of contours underneath the water A tracing on the wall showed this work. It showed the lines of soundings taken and the different systems used in locating the boat, and the practical work of the sextant in locating these points.

This covered the principal features of this summer school work. There were, however, other points that were taken up. The barometic work was very useful. Several aneroids were taken along with the party so that the students become familiar with them, and there is no need of cautioning them on the results obtained by the aneroid after they have used four. Photographic work in connection with surveying was also an incident in the summer school work. The use of the rangefinder for measuring long distances was also taught. This was borrowed from the artillery service, and four forms of range finder were used so as to see which would give the best results.

This work was confined to four weeks. Each student had about an equal amount of time for each

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class of work, the work was prosecuted throughout the whole of each day and the students were changed from one class of work to another, but by means of lectures in the evening the work of the whole school was brought before the students, and it was surprising to see how stimulating it was to see the results as reported from the plane tabling and soundings. The speaker advocated the use of the plane table in the summer school, even if it was not the most useful instrument, simply to keep up the interest of the students.

The keeping of accurate field notes was, of course, insisted on, and he thought the only thing that he could add in regard to the plea of vacation work was that it came at a time when the student has just finished his heaviest mental labor; when his mind is most active and his body has had the least amount of exercise. Here was a chance for a perfect rest without idleness, and he had found that their students never complained of being tired of this work when it was arranged in this way.

DISCUSSION.

PROFESSOR J. B. JOHNSON said he had been very much interested in the description of this work, and he doubted if anyone could improve on the methods that had been presented. He believed it was coming to be a common practice to take a portion of the summer vacation for this survey practice work. He felt that there must be a period of field work that is continuous, away from the school and from the homes of the students, where they can put in a period of three or four weeks continuously, and in a business way. He considered it was absolutely necessary also to the proper finishing up of the study of surveying for civil engineering students. For the other engineering courses such a knowledge of instruments as could be obtained during term time was sufficient. He did not want to make any extended remarks, except in a commendatory way, of everything that had been said, but where there are several ways of doing a thing, all may be equally good, when equally well carried out. It was hardly fair, however, to compare one method which is executed with the greatest care and perfection, with another method which perhaps is performed very poorly. So, in regard to comparing transit and stadia work with that of the plane-table, he thought that the stadia and the transit had not been dealt with fairly. The gentleman had said he could not tell anything about the results of the stadia work until after he returned from the field at the end of the season's work. The speaker thought if it was to be done in that way it should not be done at all. He always knew before he retired at night whether the work of the day checked or not. The day's work, so far as the instrument stations are concerned, should be worked up, elevations checked, and the traverse line platted that night, so that the party who goes out and takes up the work the next day knows whether he should go on with the work or revise it. He thought, therefore, the gentleman had given the transit and stadia hardly a fair showing, and that the two methods could not be compared on any such basis as that described. He had found this to be true

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