September 28, 1906.] 



SCIENCE. 



405 



water over 200 feet deep. Will this gradually- 

 applied extra load produce a gradual depres- 

 sion? This might almost seem, a crucial test, 

 and it would seem as though a few well-placed 

 and well-determined bench marks on project- 

 ing hills, or possibly triangulation tripods, in 

 the area to be submerged would answer the 

 question. And it is the hope of arousing 

 interest and causing the necessary measure- 

 ments to be made that has spurred me to 

 write this note. Alfred C. Lane. 



THE GEOGRAPHICAL DISTRIBUTION OF STUDENTS. 



In the article on ' The Geographical Distri- 

 bution of the Student Body at a number of 

 Eastern and Western Universities and East- 

 ern Colleges/ which appeared in the issue of 

 Science for August 10, 1906, I neglected to 

 call attention to the fact that the showing of 

 a number of the state universities is some- 

 what misleading, for the reason that many 

 students from outside the state in which the 

 university is located endeavor to establish a 

 state residence, in order to escape the tuition 

 charged to outsiders. This is true particu- 

 larly with reference to the University of Cali- 

 fornia, on account of the isolation and the 

 large size of the state. Families of students 

 from outside often establish a temporary resi- 

 dence in Berkeley, and a similar state of affairs 

 no doubt exists with reference to the Univer- 

 sity of Michigan and other state universities. 

 At California not over one quarter of the 

 students coming to the university from out- 

 side the state and from foreign countries are 

 so registered. Kudolp Tombo, Jr. 



Registrar. 



SPECIAL ARTICLES. 

 THE PRESERVATION OP SURFACE CONDENSER TUBES 

 IN PLANTS USING SALT OR CONTAMI- 

 NATED WATER CIRCULATION.^ 



The prevention of electrolytic corrosion of 

 condenser parts where they are subject to con- 

 tact with condensing water that contains elec- 



^ Read at the Ithaca meeting of the American 

 Association for the Advancement of Science, June 

 29, 1906, before Section D — ^Mechanical Science 

 Engineering. 



trolytic properties has been a serious problem 

 with condenser engineers at sea as well as on 

 land, where the condensing water contains 

 salts in solution. This action is especially 

 destructive where the cooling water is contami- 

 nated further with chemicals or with sewage. 



In the great steam plants of New York city 

 where the water bills extend into thousands of 

 dollars per annum, in fact, are approximately 

 one tenth of the fuel bills, this is an important 

 condition bearing upon the cost of the hourly 

 power unit, but the attempt to use surface 

 condensers in the past for the purpose of 

 saving this waste has not been accompanied 

 with any degree of success. The highest 

 economy demands such precautions as shall 

 leave the hot-well water coming from the con- 

 densers in a proper condition for feeding the 

 boilers. 



The waste incident to the inability to save 

 this water in stationary generating plants has 

 caused the construction of surface condensing 

 apparatus at such plants as that of the Brook- 

 lyn Edison Company at Bayridge, and of the 

 Metropolitan Street Railway Company at 

 96th Street, New York City. 



At the time the design of the Long Island 

 City Power House of the Pennsylvania Rail- 

 road was undertaken, it became evident that 

 true economy in the operation of a plant 

 which would have under ordinary circum- 

 stances an annual water bill of about $100,000, 

 when the plant has been fully put into service, 

 justified an attempt to save the water from 

 the hot well for replenishing the boilers. This 

 seemed to demand a thorough investigation of 

 the matter of condenser protection where the 

 circulation cooling water was an electrolyte 

 as it was in this case. 



The site where this plant was to be con- 

 structed was at Long Island City near the 

 harbor front, and the plant was designed to 

 contain, when fully constructed, fourteen 

 5,500 K.W. generating units. With such an 

 equipment and with an ordinary loading, the 

 amount of boiler feed water required per an- 

 num would cost in the neighborhood of 

 $100,000. 



In the investigation of possible methods for 



