726 



SCIENCE. 



[N. S. Vol. XXI. No. 541. 



the tests were made were of 1,500 kw. 

 capacity and were located at the Manches- 

 ter Street Station of the Rhode Island Co., 

 Providence, R. I. Large counterweights 

 had been placed on the engines in order to 

 reduce the amount that they shook the 

 building. It was shown theoretically that 

 when the generators were coupled together 

 with the counterweights opposed, or at 180° 

 from each other, the angular displacement 

 was about twice what it would have been 

 without the counterweights. The maxi- 

 mum displacement due to counterweight 

 action and to irregularity in the effort ex- 

 erted on the crank shaft was found by 

 theory to be 3.2 pole degrees and by ob- 

 servation from 3 to 4 pole degrees. The 

 amount of angular displacement was ob- 

 served to be the same, irrespective of the 

 position of the counterweights, but when 

 the counterweights were opposed the dis- 

 placements occurred every stroke, or about 

 94 times per minute, whereas, when the 

 counterweights were together, or nearly so, 

 the displacements occurred at less frequent 

 intervals, or about 30 to 40 times per 

 minute. As the total displacement of the 

 two fields' from their true positions, as ob- 

 served, was about the same irrespective of 

 the relative positions of the two counter- 

 weights, it follows that this displacement 

 was produced as much through governor 

 action as through any variation in the turn- 

 ing effort during a single revolution. 



On Thursday afternoon, under the able 

 guidance of Professor Marburg, the mem- 

 bers of the section were guests at luncheon 

 of the contractor for the Belmont Filtration 

 Plant. After enjoying the social features 

 of the afternoon, the members of the party 

 were conducted through the gate house, 

 filtering galleries, and had the details of 

 the operation explained to them in much 

 detail by Mr. John W. Hill, chief engineer 

 of the bureau of filtration, and his son. 

 The observations of the afternoon made the 



succeeding illustrations of the evening 

 much more real and valuable to those who 

 had the privilege of hearing both the after- 

 noon demonstrations and the evening lec- 

 ture. 



The Thursday evening session of Section 

 D was devoted to three extremely valuable 

 papers by notable engineers of the city of 

 Philadelphia, on subjects which are of 

 much interest, both to engineers and citi- 

 zens of Philadelphia and to engineers and 

 scientists at large. They were very fully 

 illustrated by lantern slides. The first 

 was by J. W. Hill, chief engineer of the 

 Bureau of Filtration of the Department of 

 Public Works of Philadelphia, and was on 

 'The Philadelphia Filtration System.' 



The second paper of the evening was by 

 Wm. S. Twining, chief engineer of the 

 Philadelphia Rapid Transit Co., and de- 

 scribed and illustrated 'The Subway and 

 Elevated Railroad of the Philadelphia 

 Rapid Transit Company.' 



The third paper was by George H. Web- 

 ster, chief engineer, bureau' of surveys of 

 the board of public works of Philadelphia, 

 and was on ']\Iodern Engineering in the 

 City of Philadelphia, under the Direction 

 of the Bureau of Surveys.' 



These papers were both most entertain- 

 ing and instructive, and showed the great 

 advances which have been made in the prac- 

 tical applications of engineering science in 

 the municipal affairs of the city of Phila- 

 dephia in providing for the citizens a 

 healthful water supply, rapid and con- 

 venient methods of transportation, and up- 

 to-date and modern methods of keeping 

 records and performing the routine work 

 of the office of city engineer in a lai'ge 

 municipality. 



The first paper on the program of Fri- 

 day morning, December 30, was by Arthur 

 H. Blanehard, assistant professor of civil 

 engineering, Brown University, Provi- 

 dence, R. I., and was on ' The Development 



