328 



8CIENGU. 



[Vol. YI., No. 141. 



tion was also made at this place and a stop-watch 

 record was taken by Professor Clarke. 



Professor Paul established himseK with a mer- 

 cury apparatus on Staten Island, about fifteen 

 miles away. Professor Hallock, of the geological 

 survey, who joined the party at New York, occu- 

 pied a station at Yonkers, distant about ten miles, 

 where he was fortunate in securing the co-opera- 

 tion of Mr. Thomas Ewing, Jr., of Columbia col- 

 lege. Mr. Hallock observed with a mercury 

 apparatus and chronometer ; and Mr. Ewing used a 

 seismoscope, noting the time of the ' drop ' by a 

 stop watch. Professor Rees of Columbia entered 

 enthusiastically into the work, and used a seismo- 

 scope with a chronograph and a mercury apparatus 

 with chronometer at the college observatory. It 

 was planned to place an observer at the meteoro- 

 logical observatory in Central park, opportunity 

 for which had been kindly offered by Dr. Draper, 

 but at the last moment no one was available for 

 that point. Dr. Draper, however, made a num- 

 ber of interesting observations on the behavior of 

 his self -registering meteorological instruments, get- 

 ting a record of the shock from nearly all of them. 

 Astronomical observatories in the vicinity of New 

 York had been notified ; and, in a number of them, 

 observers were anxiously awaiting the appear- 

 ance of the ripple on the surface of the mercury. 



Unfortunately the firing of the mine was de- 

 layed nearly fourteen minutes. This, however, 

 did not prevent good observations at several points. 

 From Ward's Island the movements of the men 

 on Flood Pock were easily noted, and the observer 

 was not obliged to begin his watch imtil the last 

 steamer had left the rock, and it was known that 

 the explosion could be expected very soon. 



It is impossible to describe the appearance of the 

 river an instant after the mine was fired. A mass 

 of water covering several acres seemed to have 

 been instantly hfted to a height variously esti- 

 mated at from one hundred to two hundred and 

 fifty feet. It has been several times described as 

 resembling a gigantic iceberg ; and for a moment 

 no more fitting term could have been apphed. 

 The seismoscope left its record of the initial dis- 

 turbance on the cln-onograph sheet, and behaved 

 throughout in a most satisfactory manner. 



At Yonkers, in spite of a prolonged observation, 

 covering about eighteen minutes, the wave was 

 ' caught ' by both the mercury dish and the seis- 

 moscope, the times observed agreeing within one- 

 fourth of a second. The seismoscope used by 

 Professor Rees and his assistant, Mr. Jacobi, at 

 Columbia college, recorded the passage of several 

 railway trains before the explosion occurred ; but 

 it was always reset, and did its work promptly 

 when the time arrived. The long delay was the 



cause of a failure at the Staten Island station, occu- 

 pied by Professor Paul. He recorded in his note- 

 book a disturbance of the mercury at about three 

 minutes past eleven, but expressed his doubt as to 

 its being due to the explosion. After waiting six 

 or eight minutes, he decided that this disturbance 

 was genuine, or that the explosion had occurred 

 and had failed to reach him, and ceased his 

 observations. It is greatly to be regretted that a 

 record was not secured on Staten Island, as it 

 would unquestionably have been, had the event oc- 

 curred within a reasonable limit of the moment 

 previously fixed. Observers at astronomical ob- 

 servatories away from New York have not yet 

 been directly heard from, but it is feared that the 

 delay of fourteen minutes prevented observations 

 being made at many points where the wave might 

 be expected to make itself felt. The telegraph re- 

 ports an observation at New Brunswick, which 

 was doubtless, like Professor Paul's, due to some 

 other cause, and which prevented the observer 

 from afterward getting the true wave. But report 

 comes in the same way that Professors Young, 

 Rockwood, and McNeill, were entirely successful at 

 Princeton. Altogether it is believed that a suffi- 

 cient number of reliable observations will be re- 

 ported to be of great value, and the results of their 

 reduction will be looked for with much interest. 



It is not likely that another opportunity of this 

 kind will occur in the near future ; but from the 

 experience of this occasion it is easy to see the im- 

 portance of having the origin of the disturbance 

 surrounded by a considerable number of stations 

 at varying distances, at each of which a seismo- 

 scope with chronograph is used, so that where 

 possible the record may be automatic ; and it 

 would also be extremely desirable to arrange that 

 those in charge of the firing should agree to some 

 plan, by means of which if the explosion did not 

 occur at a definite hour previously announced, it 

 should be postponed for ten minutes, and if not 

 then ready, for another ten, and so on. In this 

 way observers at a distance would be almost certain 

 of success. 



It ought to be added that the work of planntug 

 and arranging for the observations above noted 

 was necessarily hurried, that it was undertaken 

 and carried out imder circumstances by no means 

 favorable, and that it falls far short of what was 

 desired and hoped for by those engaged in it. 



T. C. Mendenhall. 



DISINFECTION. 



Disinfection consists in the destruction of some- 

 thing infectious, and we fail to see any justifica- 

 tion for the popular use of the term which makes 



