82 The Causes and Phenomena of Earthquakes. 



July, as reported to me by the Astronomer, and at Nundle on 

 the 30th July, then we may rightly conclude that the agitation 

 was more prolonged than was at first supposed. 



I have carefully compared all the published and many private 

 statements, and I find that the average results give from three to 

 five vibrations, lasting from two to four seconds ; for we must 

 reject some, which make the vibrations last a minute and more, 

 arising from the difficulty to persons aroused from sleep of ascer- 

 taining time accurately. The noises heard are variously des- 

 cribed ; but that heard by myself is mentioned by several obser- 

 vers at a great distance, and one mentions the noise as of artillery 

 firing ; others refer it to that of waggons, omnibuses or railway 

 carriages ; but the heavy blast, sudden stoppage of motion, a 

 charge as of cavalry, a heavy blow upon the roof, &c, show that 

 there was an explosion, independent of the low rumbling sound 

 heard by others. One observer speaks of a metallic clanging 

 sound upon the metal roof of his house. " A brazen sound 

 (oeneus clangor)'" is spoken by Cornelius Gemma, on 31st March, 

 1554, during a violent shock in Belgium." 



Mr. Bolding, of Raymond Terrace, has given me a valuable 

 account of the noises and other phenomena experienced by him, 

 and of a singular clapping in the air. The time was variously 

 assigned, but the average is midnight. It is impossible that at 

 Minmi (as stated) it could be at a few minutes after 12 o'clock, 

 when (as is also stated) it was at 5 minutes before at Wallsend. 

 The direction is given variously from E. to W., N.E. to S.W., 

 N.W. to S.E., N. to S., and from S. to N. But the greater 

 number make it as I have assumed it to have been from direct 

 observation, from N.E. or a little E. of it towards S.W. the 

 motions at right angles to this direction being the transverse 

 effects. Unquestionably it was felt more violently about the 

 lower Hunter than elsewhere, and the heaA^ing of the earth was 

 distinctly perceived at Newcastle and Raymond Terrace. The 

 swinging of the lamp noticed at Townhead, near Singleton, is 

 paralleled, by the swinging of chandeliers in churches at Amster- 

 dam, during the Lisbon earthquake of 31st March, 1761, and in 

 a church at Rotterdam during a shock at the end of January, 

 1S04. 



It is stated that no effect was produced on 18th June, on the 

 instruments at the Sydney Observatory. 



But this is of no importance, as during the great earthquake 

 that shook all central France on 5th July, 1841, it is distinctly 

 mentioued, " no effect of any note was produced on the 

 instruments of the Observatory at Paris," whilst in the depart- 

 ment of the Indre, " a clock which had been stopped in February, 

 1840, and had been left so, was again set in motion by that earth- 

 quake, and struck the hours ' ' — a fact also stated in the report 



