July 28, 1887] 



NATURE 



\o\ 



It is obvious that the phase which it is desired to 



observe should be the arrival of the first impulses. But 



the great duration of the tremors has left much doubt on 



this point. Stopped clocks were plentiful all over the 



(ountry, but at what phase of the earthquake did they 



top ? So great, indeed, are the uncertainties on this point 



that the observations of intelligent men, with watches in 



their hands measuring a part of the shock and estimating 



the beginning, are in most cases to be preferred to stopped 



locks, even though we know with certainty that the 



locks had been accurate to the second. It matters little 



how we twist and turn the time data : the smallest 



estimate we can put upon the speed of propagation 



iiust prove to be a great surprise to seismologists. 



The time at Charleston of the occurrence of the main 

 shock has been fixed at gh. 1 5m. los. p.m., 75th meridian or 

 Eastern standard time.^ (All times in this paper, unless 

 otherwise specified, are reduced to that meridian.) The 

 uncertainty does not exceed ten seconds. The beginning 

 ' 'f the first tremors at Charleston was from six to eight 

 econds earlier. The time at Summerville was probably 

 less than four seconds earlier than Charleston. For all 

 localities within 200 miles the time observations are of 

 little value. So swiftly did the waves travel that a small 

 error in the time record gives a very large uncertainty in 

 the resulting speed. 



The nearest point which yields a valuable record is 

 Wytheville, Va. (286 miles).''' Mr. Howard Shriver was 

 sitting at a transit instrument, waiting for the passage of 

 a star, and at once noted the time at gh. 52m. 37s. (re- 

 duced to 75th meridian), giving a speed of about 3*3 

 miles (5300 metres) per second. There is some slight 

 uncertainty about the precise phase of the shock corre- 

 sponding to the observation. 



The Signal Service Observer at Chattanooga (332 

 miles) gives only the nearest minute for the principal 

 shock at 9h. 53m., corresponding to a speed of 3*02 miles 

 per second, or 4860 metres. 



The best observation in our possession is that of Prof. 

 Simon Newcomb himself, at Washington (450 miles), 

 who gives the time of the beginning of the shock at 

 9h. 53m. 20s., with an uncertainty not greatly exceeding 

 ten seconds. The resulting speed is 3"46 miles per 

 second, or 5570 metres. 



From Baltimore (486 miles), Mr. Richard Randolph, 

 C.E., reports a very intelligent and carefully verified 



' For European readers it seems necessary to refer briefly to the American 

 "standard time" system, which will assist them in estimating the character 

 of these time records. Throughout the Atlantic States all clocks designed 

 for accurate time-keeping are set daily to the time of the 75th meridian west 

 of Greenwich. In the Mississippi Valley they are similarly set to the time 

 of the 90th meridian ; in the Rocky Mountains to that of the 105th, and on 

 the Pacific coast t) the 120th meridian. They are called respectively, 

 Eastern, Central, Mountain, and Pacific time, and the differences are exact 

 hours. At some convenient hour every day the wires of every railroad and 

 telegraph company in the country are put into circuit with the clock of some 

 astronomical observatory (or with some standard clock controlled by an 

 astronomical clock), and time signals are sent to every railway station and 

 telegraph office. The station agents, or telegraph operators, of these com- 

 panies are held responsible that these signals are received, and that their 

 clocks are regul.ited by them daily. A failure to do .so is a breach of discip- 

 line. The greatest purveyor of accurate standard time is the Western 

 Union Telegraph Company, which furnishes it at a small charge to some 

 railways, to telephone exchanges, to town and city offices, to hotels, to private 

 corporations; in short, to anybody who wants it. For the Eastern and 

 Southern States it takes its time by a special wire from the National Observ- 

 atorj- at Washincton. The system is essentially perfect, whereby clocks can 

 be set once each day to exact standard time in ever>' railway station and 

 telegraph office in the country. And at every such station and office it is the 

 duty of somebody to see that it is carried out. How accurately this is done 

 IS another matter. It depends upon the discipline of the companies and the 

 habits of individuals, in which there are no doubt varying degrees of precision. 

 The clocks supplied are always good ones, and ought not to have daily errors 

 of over fjur or five seconds. But the best clock ever made will not keep 

 good time unless properly managed. The demand for extremely accurate 

 time throughout the greater part of the United States is enormous, and this 

 acts as a constraint iipon the companies and their employes to carry out 

 the system with precision. This same demand has led to the organization of 

 private companies in large towns and cities who receive time from the 

 Western Union Telegraph Company and purvey it to private houses, hotels, 

 merchants, workshops, &c. 



u' «r"^ distances have been measured somewhat hastily with a scale upon 

 the War JJepartment map of the United States, taking the greater epi- 

 centrum seventeen miles north-west of Chariestonas the origin. 



observation of gh. 53m. 20s. as the beginning of the 

 shock— e.xactly Prof. Newcomb's time for Washington, 

 giving a speed of 374 miles, or 6000 metres, per second. 



At Atlantic City, N.J. (552 miles), a large pendulum 

 clock in the Fothergill House stopped at gh. 54m., very 

 nearly. If this may be taken to be the beginning of the 

 shock, the speed would be 3'26 miles per second, or 5250 

 metres. 



George Wolf Holstein, Belvidere, N.J. (622 miles), 

 gives gh. 54m. for the beginning of the shock and gh. 59m. 

 for the end, and compared his watch next morning with 

 the time of the Pennsylvania Railroad. The gradual and 

 uncertain character of the beginning and end would not 

 admit of precise determination to seconds. The speed, 

 taking gh. 54m. for the beginning, would be 3"66 miles, or 

 5900 metres. 



From New York City (645 miles) and its suburban 

 towns and cities come many reports, all of which give 

 either gh. 54m. or gh. 55m. as the nearest minutes. If 

 we take, as a mean, gh. 54m. 25s. at New York and 

 Brooklyn for the beginning of the shock, the speed would 

 be 3'3i miles, or 5330 metres. 



At distances greater than 600 miles the difficulty of 

 associating the time records with particular phases of the 

 shocks becomes very great. In most cases the motion 

 was the swaying movement, with only faint tremors of the 

 rapid kind, and those who felt them were slow in recog- 

 nizing their character. Readers must form their own 

 opinions as to the degree of approximation to the time of 

 the earliest movements from the following records We 

 give them only as we received them, without attempting 

 any discussion. 



J. O. Jacot, watchmaker and jeweller, at Stockbridge, 

 Mass. (772 miles), was sitting by his regulator clock ; 

 distinctly recognized the nature of the movement, and 

 noted the time as gh. 56m. The phase of the shock is 

 uncertain. 



At Albany, N.Y. (772 miles), Mr. J. M. Clarke, of the 

 New York State Museum of Natural History, heard the 

 mortar falling down the chimney, and the creaking and 

 straining of the building. As soon as he appreciated the 

 character of the disturbance he noted the time by his 

 watch as 9h. 56m. 30s. He did not ascertain the error of 

 his watch. In the same city. Dr. Willis G. Tucker says 

 he instantly looked at his watch, and after comparing it 

 next morning with the time of the Dudley Observatory, 

 and making correction of the error, gave gh 55m., very 

 nearly, with an error probably not exceeding twenty 

 seconds. 



From Fonda, N.Y. (780 miles), Francis L. Yates reports 

 9h. 55m. (no particulars). 



At Ithaca, N.Y. (695 miles), the regulator clock on the 

 wall of the railway depot stopped at gh. 55m. " exactly." 



At Gowanda, N.Y. (666 miles), where the shocks were 

 faintly felt, W. R. Smallwood, watchmaker and jeweller, 

 noted the end of the perceptible shocks at gh. 55m. 30s. 

 by his regulator clock. 



At Toronto (753 miles), the earthquake was recorded 

 automatically upon the magnetographic traces in the 

 observatory of Prof. Chas. Carpmael, Superintendent of 

 the Meteorological Service of Canada. In his letter of 

 September 14 he says :— " I may state that at gh. 55m. p.m. 

 all our magnetic needles were set in motion by earth 

 tremors. The vibrations of the magnets were continued 

 for about four minutes. I would say that from later and 

 more careful measurements from our magnetic curves I 

 make the time of the earth tremor at Toronto to be 

 9h, 54m. 50s. p.m., standard ; this time, I should say, 

 would not be astray more than a few seconds.'' As this 

 record was automatic, and gave not only the time but the 

 phases, it has been thoroughly investigated by Profs. 

 Newcomb and Carpmael, assisted by Mr. C. A. Schott, 

 of the U.S. Coast Survey. The final result of this re- 

 examination is to change Prof. Carpmael's computation 



