more attention than usual, shall be stated with as much precision as it is possible to obtain, from the report of those practical miners only who have hitherto inspected them. "The facts which deserve to be first noticed are, the confined and insulated position of the mass of silver ore; its great depth from the surface of the mine; and its dontiguity to a copper lode. "The lode in which it occurs is one of those cross courses, as they are here called, which intersect and derange the copper lodes, and consequently are of a more reeent formation.. "Lodes in this direction are usually filled with quartz, but frequently produce galena; and sometimes, instead of galena, sulphurated antimony. They appear here to conform to the same laws, except in the particular instance now to be described, which forms, indeed, a very remarkable exception... No ores in silver were observable in this lode, until at the depth of one hundred and ten Fathoms from the surface, or eighty below the adit or level; and, at the further depth of thirty-two fathoms, they disappeared.. "They have been discovered only in the neighbourhood of one of the intersected copper lodes, extending no where above twelve feet from this lode, on the north, or above thirty-two feet from it, on the south, and acquiring this their greatest extent at the deepest level; for, the usual dimensions of the silver ore are not more than six feet in the former situation, and twelve feet in the latter. "It is remarkable, that at the point of contact or intersection, the contents of the silver lode are so poor as to be scarcely worth saving; and those of the copper lode are much less productive of copper than at a little distance from this point. Moreover, that the copper lode, in the vicinity of the intersection, seems to have been influenced by the same causes of improvement and declension as the cross lode; being richer or poorer in copper, as the latter was, at a correspondent level, in silver. "The richest mass of silver ore was found at the depth of two fathoms above the level at which it disappears. "After this brief account of the most striking facts, it may be pro-. per to enter into a more particular description of the two lodes which appear, by their intersection, to have generated this body of extranecus matter. "The copper lode bears nearly east and west by the compass; the cross lode nearly north and south, or at right angles to it. "The former is about two feet broad, on an average: and it dips of underlies south, one foot in a fathom. The breadth of the latter is about two feet and a half, on an average; and its underlie is east, about eight inches in a fathom. "The heave of the copper lode is about eighteen or twenty inches to the right, in the language of the Cornish miner; the expression being so far appropriate and convenient, as it refers to the usual situation of the observer in the heaved lode. "The copper lode is filled with layers of ore and stony matter, the latter of which is here called caple; but the ore is usually found contiguous to the walls of the lode. "The contents of the cross lode are more singular, in respect to their local position, and more various. Only the eastern side of it produces produces silver ore, the breadth of which is in general about six or eight inches, although in some places it is greater. The other part of the lode is chiefly composed of quartz, intermixed with iron, manganese, and wolfram, together with a small portion of cobalt and antimony.. "The silver ore, strictly speaking, is a mixture of galena, native bismuth, grey cobalt ore, vitreous silver ore, and native silver; which, in respect to their proportions, follow the order in which they are here enumerated, the galena being the most prevalent. The native silver, of which specimens of the greatest beauty have been reserved for the cabinets of the curious, is found chiefly in a capillary form, in the natural cavities of the lode. "About one hundred and eight tons of this ore have been raised. The miners continue to sink near the same point of intersection; and seem confident that both lodes will soon become richer, because similar instances of declension and recovery have frequently occurred in the copper lodes of this mine, and because the two lodes appear to have a reciprocal influence on each other. "Unfortunately, however, the extent of their speculation is limited by the great depth of the present workings; for, forty-five fathoms have been sunk since the first discovery of the silver; and twenty, or twenty-five fathoms more, are as much as can be sunk in this mine, with its present mechanical powers of drawing the water; at which level, viz. one hundred and eighty fathoms from the surface, it would be somewhat deeper than any mine in Cornwall, and about one hundred and thirty fathoms below the level of the sea, at low water mark. "The other cross lodes in this mine produce no silver; most of them being flookans, or lodes which are essentially different from the argentiferous cross lode, in the nature of their constituent mass. There is one, however, in the eastern part of the mine, which, from its resemblance to that, is thought likely to produce silver, whenever it shall be explored to the same depth, at its point of intersection; although these hopes may probably be fallacious, for the argentiferous lode intersects five other copper lodes, viz. two on the north, and three on the south side, without producing any silver." CONCLUSION of DR. HERSCHEL'S OBSERVATIONS to investigate the NATURE of the SUN. [From the PHILOSOPHICAL TRANSACTIONS for 1801, Part II.] ROM these two last sets of establishes the scarcity of the lu- think we may reasonably conclude, ference in the emission of light and heat from the sun. It appears to taphor, me, if I may be permitted the me K 4 taphor, that our sun has for some time past been labouring under an indisposition, from which it is now in a fair way of recovering. An application of the foregoing method, however, even if we were perfectly assured of its being well founded, will still remain attended with considerable difficulties. "We see how, in that simple instrument the barometer, our expectations of rain or fair weather, are only to be had by a consideration of many circumstances, besides its actual elevation at the moment of inspection. "The tides also present us with the most complicated varieties in their greatest elevation, as well as in the time when they happen on the coasts of different parts of this globe. The simplicity of their cause, the solar and lunar attractions, we might have expected, would have precluded every extraordinary and seemingly discordant result. "In a much higher degree, may the influence of more or less light and heat from the sun, be liable to produce a great variety in the severity or mildness of the seasons of different climates, and under different local circumstances; yet, when many things which are already known to affect the tempe rature of different countries, and others which future attention may still discover, come to be properly combined with the results we pro pose to draw from solar observations, we may possibly find this subject less intricate than we might apprehend on a first view of it. 66 If, for instance, we should have a warm summer in this country, when phenomena observed in the sun indicate the expectation of it, I should by no means consider it as an insurmountable ob jection, if it were shown that n another country the weather had not been so favourable. And, if it were generally found that our prognostication from solar observations held good in any one given place, I should be ready to say that, with proper modifications, they would equally succeed in every other situation. "Before we can generalise the influence of a certain cause, we ought to confine our experiment to one permanent situation, where local circumstances may be supposed to act nearly alike at all times, which will remove a number of difficulties. "To recur to our instance of the tides, if we were to examine the phenomena which they offer to our inspection in any one given place, such as the mouth of the Thames, we should soon be convinced of their agreement with the motion of the sun and moon. A little reflexion would easily reconcile us to every deviation from regularity, by taking into account the direction and violence of winds, the situation of the coast, and other circumstances. Nor should we doubt the truth of the theory of the tides, though high water at Bristol, Li, verpool, or Hull, should have been very deficient, at a time when, in the place of our experiments, it had happened to be uncommonly abundant. "Now, with regard to the effects of the influence of the sun, we know already, that in the same latitudes the seasons differ widely in temperature: that it is not hot test at noon, or coldest at midnight; that the shortest day is neither attended with the severest frosts, nor the longest day with the most oppressing heats; that large forests, lakes, morasses, and swamps, affect the temperature one way; and rocky, sandy, gravelly, and barren situations, in a contrary manner; that the seasons of islands are considerably diffeent from those of large continents, and so forth. "But it will now be necessary to examine the accounts we already have of the appearance and disappearance of the solar spots, and to compare them with the temperature of the respective times, as far as history will furnish us with records. "The first thing which appears from astronomical observations is, that the periods of the disappearance of spots on the sun are of much shorter duration than those of their appearante; so that, if the symptoms which have been pointed out, as denoting the state of the sun with regard to light and heat, should be well founded, we ought rather to look upon the absence of spots as a sign of deficiency, than on their presence as one of abundance; and this would justify my expression, of the recovery of the sun from an indisposition, as being a return to its usual splendor. "In going back to early observations, we cannot expect to meet with a record of such minute phenomena as we have attended to. The method of viewing spots on the sun, by throwing their picture, in a dark room, on a sheet of white paper, is not capable of delicacy; nor were the direct views of former astronomers so distinct as, in the present improved state of the telescope, we can have them; a very imperfect account of solar spots may therefore be ex pected, considering our present inquiry, which would require complete observations of every spot, great or small, that has been on the sun during such periods as will be examined. "With regard to the contemporary severity and mildness of the seasons, it will hardly be necessary to remark, that nothing decisive can be obtained. But, if we are deficient here, an indirect source of information is opened to us, by applying to the influence of the sun-beams on the vegetation of wheat in this country. I do not mean to say, that this is a real criterion of the quantity of light and heat emanated from the sun; much less will the price of this article completely represent the scarcity or abundance of the absolute pro duce of the country. For the price of commodities will certainly be regulated by the demand for them; and this we know is liable to be affected by many fortuitous circumstances. However, although an argument drawn from a well ascertained price of wheat, may not apply directly to our present purpose, yet, admitting the sun to be the ultimate fountain of fertility, this subject may deserve a short investigation, especially as, for want of proper thermometrical observations, no other method is left for our choice. "Our historical account of the disappearance of the spots in the sun, contains five very irregular and very unequal periods *. The first takes in a series of twentyone years, from 1650 to 1670, both included. But it is so imperfectly recorded, that it is hardly safe to draw any conclusions from it; for "See Astronomie par M. de Lalande, § 3235." we we have only a few observations of one or two spots that were seen in all that time, and those were only observed for a short continuance. However, on examining the table of the prices of the quarter of nine bushels of the best or highest priced wheat at Windsor, marked in Dr. Adam Smith's va luable Inquiry into the Nature and Causes of the Wealth of Nations*, we find that wheat, during the time of the twenty-one years above mentioned, bore a very high price; the average of the quarter being 21. 10s. 51d. This period is much too long to suppose that we might safely compare it with a preceding ar following one of equal duration. Besides, no particulars having been given of the time preceding, except that spots in the sun, a good while before, began to grow very scarce, there might even be fewer of them than from the year 1650 to 1670. Of the twenty-one years immediately following, we know that they certainly comprehend two short periods, in which there were no spots on the sun; of these, more will be said hereafter; but, including even them, we have the average price of wheat, from 1671 to 1691, only 21. 4s. 43d. the quarter. The difference, which is a little more than as nine to eight, is therefore still a proof of a temporary scarcity. "Our next period is much better ascertained. It begins in December 1676, which year therefore we should not take in, and goes to April 1684; in all which time, Flamsteed, who was then observing, saw no spot in the sun. The average price of wheat, during these eight years, was 21. 7s. 7 d. the quarter. We cannot justly compare this price with that of the preceding eight years, as some of the former years of scarcity would come into that period; but the eight years immediately following, that is, from 1685 to 1691, both included, give an average price of no more than 17. 17s. 1d. The difference, which is as full five to four, is well deserving our notice. "A third but very short period, is from the year 1686 to 1688, in which time Cassini could find no spot in the sun. If both years be included, we have the average price of wheat, for those three years, 1. 15s. 03d. the quarter. We ought not to compare this price with that of the three preceding years, as two of them be long to the preceding period of scarcity; but the three following years give the average price for the quarter of wheat 11. 128. 103d. or, as nearly eleven to ten. "The fourth period on record, is from the year 1695 to 1700, in which time no spot could be found in the sun. This makes a period of five years; for, in 1700 the spots were seen again. The average price of wheat, in these years, was 31. 3s. 34d. the quarter. The five preceding years, from 1690 to 1694, give 21. 9s. 4td. and the five following years, from 1700 to 1704, give 1. 17s. 11d. These differences are both very considerable; the last is not less than five to three. "The fifth period extends from 1710 to 1713; but here there was one spot seen in 1710, none in 1711 and 1712, and again one spot only in 1713. The account of the average price of wheat, for these "See book i. chap, xi." four |