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has been thought past, and all that remains of the care of years is a pile of rust-coloured leaves in place of the tender green which yesterday delighted the eye.

The finest plant with which I am acquainted near Edinburgh, is one in Mr Samuel Hay's lawn at Trinity Lodge. It is a beautifully shaped conical tree, nearly 13 feet in height. The next in height, perhaps, is one at Mr George Logan's of Duddingston, which is about 11 feet.

Mr Humphrey Graham, of Belstane, in the Pentland Hills, from whom I have received much valuable information regarding pines (although of too practical a nature to be introduced into this Journal), under the disadvantage of an almost subalpine climate 800 feet above the level of the sea, promised to be more successful in rearing them than any other person in the middle or northern district of Scotland with whom I am acquainted, but even he had all his plants but two swept off by the frost in 1856. He is not discouraged, however, and he reports to me that he is still satisfied it will succeed in Scotland, if tolerable care be taken.

The timber is not good. I remember my brother telling me when he was last in this country that it was useless. It would appear, however, that a use has now been found for it. In a recent letter he writes, "the street planking here (San Francisco) used to be done with Oregon lumber, but now it is being superseded by the Monterey lumber (most likely P. insignis) for the reason that it is very resinous, and stands the wear and tear of such a purpose better."

PINUS JEFFREYI, Oreg. Com. (Plates VIII. and IX.)

This pine was discovered by Mr Jeffrey, who was sent out in 1850 to collect seeds in North West America by an association of gentlemen which originated in this city, and was principally composed of Scotchmen, although it also numbered in its body many noble and eminent subscribers from the sister kingdom, chief of whom I should mention, His Royal Highness the Prince Consort. That association still lives in its embers, and I trust that an effort now making to revive it may be successful, and that it may yet make as many discoveries in Japan as it did through Jeffrey in Oregon and California. Some

subscribers to the association remembering only that the third and last year of Jeffrey's engagement terminated unsuccessfully, and that they had just reason to be dissatisfied with his conduct during that year, sometimes speak of his expedition as a failure. But it is unjust so to term it; and if they would only remember the quantities of novelties which were discovered and introduced through his means, they would rather treat it as a great success, which only assumes the aspect of a partial failure from the knowledge that, great as it was, it ought to have been, and might have been, greater still. No one could have worked more conscientiously and more perseveringly than Jeffrey did during the first two years of his employment, and bearing in mind the fact that Menzies and Douglas went to a virgin country, his collections do him no discredit, even as compared with theirs. He discovered several new pines, six of which were described by Professor Balfour, along with figures by Dr Greville, in one of the Reports of the Oregon Committee, and two or three more still remain undescribed. The Report of the Oregon Committee having been only issued to its shareholders, cannot, perhaps, be strictly said to be published, at least I understand that some scientific purists so maintain, although I am not sure that they are right, since I see little difference between a printed report to an association sent to its subscribers, and a printed book (published by subscription) sent to its subscribers. But be that as it may, Mr Gordon has published the description of this pine in his work, and its name and identity are thereby secured. He has not, however, given the figure of the cone, which is one of the most perfectly beautiful I have ever seen.

As I have received a sketch of the tree itself, taken by Mr Peebles, which I have caused to be lithographed for this paper (Plate VIII.), I have thought it desirable at the same time to reproduce the figure of the cone (Plate IX.)

Jeffrey found the tree in Shasta Valley, North California, lat. 41.30°. It has also been found in Scots Valley; and Mr Black, whom I shall have presently to mention, found it near Mariposa. It is a fine tree, 150 feet in height, and 4 feet in diameter. It has not yet been found near enough any

of the cities to allow of the economic value of its wood being ascertained.

PINUS MURRAYANA, Oreg. Com.

This is another of the species discovered by Jeffrey, and described by Professor Balfour in the Report of the Oregon Committee. Mr Gordon, however, disallows it, placing it as a synonyme of P. muricata, but without stating the grounds on which he has come to that opinion. It appears to me very distinct; and although I have, as in the case of P. radiata and P. insignis, the advantage of additional and better material to form a judgment upon than probably was in Mr Gordon's hands, I can scarcely acquit him of hastiness in coming to the conclusion he has arrived at. He gives a correct account of the locality where the true P. muricata was found, viz., in the mountains of Monterey, mountains not higher than 3000 feet, and situated near the sea, and south of San Francisco; and also states correctly where Jeffrey had found, what the Oregon Committee called P. Murrayana, viz., on the Syskyon Mountains, far north of San Francisco, at an elevation of 7500 feet above the level of the sea; and the tree is described as being at both of these places about 40 feet high. Now, one of the facts with regard to the distribution of conifers in California, which must have struck any one who has studied the subject, and with which Mr Gordon cannot fail to be familiar, is that, taking San Francisco as a point, the pine vegetation to the north and south of it, making a certain allowance for transitional portions, is essentially distinct. In the latitude of San Francisco, we have the P. Sabiniana,-to the south of it, P. Coulteri, P. insignis, P. muricata, P. bracteata, &c. North of it their place is supplied by Picea nobilis and grandis, Pinus monticola, P. tuberculata, P. Jeffreyi, &c.; and the very circumstances of the one being found at an elevation of 7500 feet, so far north as the Syskyon Mountains, and growing near the sea, at an elevation of 3000, so far south as Monterey, ought to have put Mr Gordon on his guard against confounding them.

Without going into minute detail as to the differences between the two, I shall only observe, that the cone of P. muri

cata is 3 inches in length; while a pretty extensive series of P. Murrayana enables me to say, that its dimensions are from 1 to 2 inches in length. Again, P. Murrayana has a very peculiar long spine, or rather prickle, from 1 to 2 lines in length, sticking outwards and backwards from the middle of each scale; while P. muricata has only "a slight ridge running across the scales near the top, terminated by a short, straight broad prickle in the centre." In the specimens of P. Murrayana which were received from Jeffrey, these spines were broken off, and the cone is so figured, and Mr Gordon is not responsible for the error thence arising; but they are well marked in specimens since sent, more than once, by my brother, and now in the Museum of the Botanic Garden, and in that of Messrs Lawson.

Mr Gordon says, that it is the Obispo or Bishop's Pine, and perfectly hardy. This is only half true. The P. muricata is the Bishop's Pine, and the P. Murrayana is perfectly hardy. That the P. muricata is hardy, is more doubtful.

There is another pine known to horticulturists as P. M'Intoshiana, which Mr Gordon considers synonymous with P. contorta, Don, but which I think is more likely to prove synonymous with P. Murrayana. In the young state they are undistinguishable; but I have not seen the cone of P. M'In

toshiana.

Mr Black, an English engineer who had occasion, in the performance of works entrusted to him in California, to make use of various of the country woods, informs my brother, that P. Murrayana is the best wood in the country for railway sleepers, sluice-heads, and purposes where a hard and durable wood is required; but being of a small growth, and more knotty than some of the others, is not so good for planks, and what is technically known by the term lumber. He also mentions as a peculiarity in it, that the rings are more concentrated at the outside than at the heart, which he says is just the reverse of the others, only of some of them however, for we shall find that this is also the case with Wellingtonia gigantea. He suggests that it may indicate a rapid growth when young, and slow afterwards, owing, perhaps, to the scantiness of the soil in the rocky regions where it grows.

228

On the Incorrectness of the Present Mode of Estimating the Mean Temperature in England. By JAMES STARK, M.D., F.R.S.E., &c., &c.*

As in other sciences, meteorologists are very apt to be led by a name; and provided a practice be recommended by some one who, from his position or otherwise, has acquired a name, his recommendation is adopted without examination, even to the damage of the science itself. Such is the case with regard to the mode of estimating the mean temperature at present followed in England. Mr Glaisher, who occupies the position of Meteorologist in Greenwich Observatory, and Secretary to the Meteorological Society of England, has recommended, and has for years followed, the practice of estimating the mean temperature by taking it as the mean of the united observations. made by the self-registering and common thermometers-the exact mean of the observations made by each of these instruments being first altered by certain tables which he has constructed for the purpose of correcting them for what he terms diurnal range.

Let us look into this subject a little, and see the facts on which such corrections are made; and the principle involved in making the altered observations of one instrument made the basis for the correction of another and more trustworthy instrument, whose indications are at all times steady, and free from the liability to error to which the other is subject if not read at the exact hour and minute of time when the observation ought to have been made.

At Greenwich, from 1840 to 1845, a series of thermometric observations was made with the common dry-bulb thermometer alongside of the wet-bulb, the readings being taken every second hour of Göttingen mean time. It was inferred, but without any proof that such is the case, that the mean of these twelve readings in the twenty-four hours would give the true mean temperature of the day, although it was known that these readings would almost invariably miss the period when the greatest heat of the day occurred; so that from this cir

*Read before the Royal Society of Edinburgh, 16th January 1860.

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