But it may only be found in detached pockets of greater or less extent, and irregularly distributed throughout the valley; even in this case it will be of great value and amply repay for many years to come skilful and judicious labour. The proprietors are about to open shafts and to erect suitable machinery for working them to the north of the present mines. These operations will determine in some measure the extent and character of the deposits. Before another year closes we may therefore hope to present to our readers a more definite account of the geological character of the Acton mines. It is evident that they are in the hands of enterprising men and are being worked with intelligence and vigour. At present they present a busy scene of active life. About 200 men, women and boys, are engaged at good wages in the various departments of the works. The strong men are busy boring and blasting and carrying off the precious fragments from the mines. Others are breaking the masses of rock into small pieces, and then a multitude of boys and girls are washing, picking, and arranging the pieces according to the quantity of copper they contain. Other workmen fill the barrels with the broken washed and selected ore; and from the mines to the Railway station at the village, there is a constant traffic of Canadian carts laden with the metallic spoils. Several thousand tons have by this time been shipped to the market at Boston. The assay of the best quality of the ore gives from 25 to 30 per cent. of copper. This is a large percentage and must prove highly remunerative to the fortunate owners. When the requisite machinery is erected for mining, crushing, washing and smelting the rock, much that cannot now be removed from the locality on account of the cost of transit to Boston will yield a workable profit, and the copper of the richest ores will become more immediately available. The quality of the Acton copper is already coming into notice and is reckoned only second to that of Lake Superior. By the enterprise of a few intelligent men, there has thus during the past year been opened up to Canada a source of industry and wealth that will not only benefit the parties immediately concerned but also the country at large. Whatever of value we can extract from the earth is a real addition to our wealth, increases our available means for the employment of human labour, and for the extension of our agriculture and commerce. The discovery of the Acton mines will, we doubt not, become an important epoch in the history of our national industry. A. F. K. ARTICLE XLVI.-Notes on the Earthquake of October, 1860. Read before the Natural History Society of Montreal, Oct. 29, 1860. On the 17th October, Canada and the Northern States of the American Union, were visited by an earthquake vibration of a more general and impressive character than any that has occurred for many years, and we propose to present to our readers such reports as have reached us with respect to its distribution, time, and local intensity, and to add for comparison and future experience a summary of the earthquakes that have occurred in Canada since its colonization, and some remarks on the laws of these phenomena as far as they have been ascertained. In Canada the earthquake of the 17th. was experienced in its greatest intensity in the lower part of the river, and with diminished force as far west as Hamilton. In the United States, in like manner, it was most violent on the Atlantic coast and extended westward apparently with less intensity as far as Troy. Between Hamilton and Father Point it was felt throughout the whole of Canada. At River Ouelle and other places in the lower St. Lawrence it was so violent as to throw down chimnies and damage walls, and several severe shocks were felt. In Upper Canada there appears to have been but one shock and this comparatively feeble. We have at present no information as to the extension of the vibrations to the north of Canada and to the south of the Northern States.* The following list of places in which observations were made of the time and intensity of the shocks has been compiled chiefly from the newspapers, to which much credit is due for the careful and intelligent manner in which they have collected and recorded the facts. The places have been arranged in the order of their longitudes, from east to west, and it will be observed that the time is earlier in eastern localities, but on comparing Bic and Belleville nearly nine degrees of longitude apart, it will be seen that the difference of time is only a little less than that due to the difference of longitude. The Hamilton observation would give an earlier time, but as the shock was slight and the testimony of only one observer was recorded, there may be an error. The shock thus appears to have been nearly simultaneous throughout Canada. It was felt in New Brunswick also. Bic, 6 a. m., Three shocks at intervals of some seconds, noise continued for 10 minutes. Green Island, 6 a. m. Rivière du Loup, 6 a. m. A series of shocks lasting nearly five minutes. A schooner off this place experienced a shock resembling that of striking on a sand-bank, and the waters of the Gulf were unusually agitated. River Ouelle, 6.15 a. m. Very violent, damaging walls and throwing down chimneys, especially in low grounds. Eboulements, near Murray Bay, 5.30 a. m. Violent. Five other feeble shocks in rapid succession, another at noon and another at 5 p. m. This is the only place where these latter shocks are mentioned, but the hour of the first is probably an error, as Bay St. Paul, quite near Eboulements, agrees in this respect more nearly with other places. Bay St. Paul, 5.50 a. m. Violent shock; chimneys fell. St. Joseph de la Beauce, 6.10 a. m. Quebec, 5.50 a. m. Several shocks, severe, especially in lower parts of the city and in the environs; but less so than at River Ouelle, &c. Leeds, Megantic, 6.10 to 6.15 a. m. Richmond, 5.45, a. m. Three Rivers, about 6 a. m. Shocks felt for two minutes. Granby, about 6 a. m. St. Hyacinthe, 5.45 a. m. Three shocks continuing more than a minute, buildings reported damaged. Maskinonge, 6 a. m. posed to be from Shocks felt for more than a minute, sup- Montreal, 5.50. Two or three perceptible shocks, felt less on the Mountain than on lower ground. St. Martin, Isle Jesus, 5.55. At Dr. Smallwood's observatory, two distinct and smart shocks. The wave passed from East to West. Barometer 29.964 inches, temperature 40° 3, wind N. E., cloudy. Cornwall, 6 a. m. Prescott, 5.30 a. m. Belleville, 5.30 a. m. One shock. Hamilton, 4.45, a. m. In all or nearly all of the above places the earthquake was pre ceded by a rumbling noise which gradually decreased after the vibrations had passed. The difference of duration ascribed to the shocks appears to arise mainly from the circumstance that some observers include the continuance of vibration in buildings, &c., as well as that of the subterranean sound; and in this way it is probable that by some persons two or more shocks have been regarded as one. The following graphic account of the phenomena as observed at River Ouelle appeared anonymously in a Quebec paper, and is the most detailed statement we have seen of the effects of the earthquake in those localities in which it was most violent, Rivière Ouelle, 17 octobre, 1860. "Ce matin trois fortes secousses de tremblement de terre sont venues jeter la frayeur au milieu de nos populations. "Les batisses situées de chaque côté de notre rivière ont souffert généralement. Une cheminée chez E. Chas. Têtu, deux chez M. C. Casgrain, une chez M. Frenette, une chez Auguste Casgrain, une chez madame Frs. Casgrain, et chez une dizaine d'autres personnes ont été renversées. La croix de notre Eglise et le coq sur qui la montait sont à terre; les murs des notre belle église sont lézardés. Les secousses étaient effrayantes; la première, la plus violente, a commencé à six heures et quart, et a duré quatre minutes et 40 secondes, très violentes durant dix secondes et s'affaiblissant graduellement; la secousse la plus faible à six heures et vingt minutes, a duré trois à quatre secondes, et la troisième a commencé a six heures et demie, et n'a duré que deux à trois secondes; mais, comme la première, c'était un choc saccadé faisant danser les meubles, décrochant les cadres, les horloges, etc. "Les secousses ont été plus faibles sur les hauteurs, que dans les plaines, de sorte que mes bâtisses se sont trouvées à l'abri des accidents. "Jamais de mémoire de nos habitants, nous n'avons eu des coups aussi forts. Je suis demeuré devant mon horloge tout le temps pour m'assurer de sa durée, afin de pouvoir computer avec d'autres endroits la marche de ce grand et terrible phénomène. "Un bruit sourd et fort nous a d'abord averti et ensuite sont venus les secousses et les craquements." The observation of Dr. Smallwood that the wave proceeded from east to west accords with that of some other observers and may be regarded as correct. At the same time the nearly simul taneous occurrence of the shock throughout Canada, perhaps indicates that the wave did not move horizontally but reached the surface from a great depth and at a high angle as Perrey seems to suppose the earthquakes of Eastern America have usually done. It must however be observed that at the rate of propagation given by Mallet for earthquake waves through hard rock, which is not less than 10,000 feet per second, it is quite possible that even a horizontal wave may appear to be felt at the same instant at great distances.* All the observers agree that the sound preceded the shock and continued after it, and that the first shock was the most violent; and it is also very generally noted that it was most severely felt on low ground and least so on rocky eminences. This last character which belongs to earthquakes generally, seems to arise from the greater resistance opposed to the vibrations by loose materials as compared with hard rocks. It appears from the published lists that the late earthquake is the last of at least twenty-nine that have visited Canada since its discovery by Europeans, and we now proceed to give some account of these previous instances, availing ourselves mainly of the facts and conclusions stated by Mallet and Perry, the two most extensive and laborious collectors of earthquake statistics. Mallet defines an earthquake as "the transit of a wave of elastic impression in any direction from verticality upward to horizontality in any azimuth through the crust of the earth, from any centre of impulse, or from more than one, and which may be attended with tidal and sound waves dependent upon the impulse and upon the circumstances of position as to sea and land." Such "earthwaves" travel outward from the centre of impulse with immense velocity and appear as upward shocks or undulating rolls according to the greater or less verticality of the motion. They may also be complicated with indirect shocks arising from unequal or circuitous transmission of the vibrations, and these complex shocks usually occur in great and destructive earthquakes. The causes of these vibratory waves are too deep-seated to be directly known to us, but they must occur when any part of the crust of the earth is subjected to tension, and when this is sudden. ly relieved by fracture or otherwise, and again when any part of the earth's crust is left unsupported and collapses under the force * See Mallet on the Dynamics of Earthquakes.-Transactions Royal Irish Academy, Vol. XXI. |