1870.] DAWSON — ON EARTHQUAKE OP OCT. 20, 1870. 285 



for a complete double vibration. The second series of vibrations 

 occurred after an interval of 5 seconds, and lasted 11 seconds. 



The direction of vibration was NNE and SSW. It was felt 

 at Boston a minute and three quarters before reaching New Haven. 

 At Cleveland, Ohio, it was felt at the same time as at New 

 Haven. " Slight vibrations were felt as far south as Richmond, 

 Va., and as far west as Dubuque, Iowa." Prof. Bell, of the 

 Geological Survey, informs me that the shock was felt at Sault St. 

 Marie, and on the North Shore of Lake Superior, and was ac- 

 companied by a cracking or rending sound in the rocks. 



The followinii" account of the Meteorolo2;ical Phenomena, 

 attending the earthquake at Montreal, is contributed by Dr. 

 Smallwood of the McGill College observatory. 



" Rain fell on the 13th day, followed by a rise in the Baro- 

 meter, and a splendid display of the Aurora Borealis on the night 

 of the 14th day. Numerous and very large spots were present on 

 the solar disc, which had been the case for some considerable 

 time, more especially during the presence of the Aurora on the 

 nights of the 23rd, 24th, 25th, and 26th days of last month 

 (September.) 



" The maximum reading of the Barometer at 7 a. m. on the 

 morning of the ICtli day, indicated 30.215 inches, and was suc- 

 ceeded by a very fine, warm day, the mean temperature of which 

 was 63.9 degrees, wind S. AV. Showers of rain fell on the 17th 

 from 10 a. m. till 3 p.m., with a west wind and with a falling 

 Barometer, which at 9 p. m. of that day stood at 30.000 inches. 

 From 1 a. m. of the 18th (Tuesday)" a very rapid and sudden fall 

 was observed, viz : 0.G39 of an inch in six hours, and it attained 

 its minimum, 29.361 inches, at 7 a.m. on that day. 



" From that hour a gradual and somewhat sudden rise took 

 place accompanied by a very heavy gale of wind. The clouds 

 were passing from the West, but the wind veered to all points of 

 the compass. The register of the Anemometer at the Observa- 

 tory shows a complete disc of concentric circles, with a velocity 

 varying from 35 to 15 miles per hour. 



'- There was also a rise of 0.507 of an inch in the Barometer, 

 with a falling temperature. Frost occurred during the night, and 

 a good breeze continued from the West. The Thermometer at 7 

 a. m. showed 33.1 degrees, and the Barometer 30.070 inches. 



" From this time the temperature rose and the Barometer fell, 

 and this moroing at 7 a. m., stood at 29 .499 inches. Rain set in 



