Returning to the decoy lamp, he says-now, there are half a dozen arrivals almost at the same time, of which two or three are good specimens of Heliophobus Popularis, and the rest are injured ones of other species. At intervals moths continue to come, sometimes singly and sometimes in numbers until at last they cease. With patient expectation we still stand by, until we think the majority, at least, have settled down to rest; or we may occupy the time in examining the adjacent bank, where, attracted by the honey-dew upon the rose-bush, moths may be feeding. With the aid of our pocket lanthorn, we look carefully over the leaves, occasionally finding a good specimen of Spalotis præcox, or an Agrotis. The large spider, too, which often abounds here, will afford amusement for an interval when there is nothing coming to the lamp; a specimen has just come to the latter, which proves to be the common Lupernia testacea. Again a pause ensues, during which we will examine the neighbouring hedge; a specimen here is the Anthocelis lunosa, and another further on is the Epunda lichenea; the latter insect is partial to resting on dead fences after dark, and may be taken in such situations more freely than in any others. A dark moth is dashing about the lamp, so we'll hasten up to secure it; it is Lupernia cespitis. In appearance, this is not an attractive species, having the anterior wings black, and the under wings rather a dirty white, giving the idea of "shabby gentility," but much prized by collectors from the rarity of the capture. This method of attracting insects may be pursued with success till winter. A keen appetite and the want of exercise make the tired entomologist feel the dewy chill which prevails after midnight. Experience has taught us that refreshment is highly beneficial, and with this in view, we have come provided with sandwiches, a can of water, and the ingredients for making coffee; the lamp supplies the fire. No doubt there are still many who think that the entomologist's rambles are a succession of pleasant walks in pursuit of gay insects, which flit about in sunshine amidst delightful flowers and fine scenery-walks! which are attended with no trouble or annoyance-walks! which while away a few pleasant hours in catching pretty things; and then, when change is wanted, a pleasant walk home again. This is certainly a popular idea which must not be entertained. The pursuit of entomology is really pleasant, but it has its drawbacks; and there are few occupations which require greater powers of mind or body. A good entomologist should possess patience, perseverance, endurance, and a fair share of ingenuity; he should be capable of much bodily exertion, and able to take long walks to his ground, where he must often combat disappointment; he must be able, too, to run, to jump hedges and ditches, to climb trees or rocks, and if necessay, to wade in brooks, ponds, or bogs. His eyes must be able to detect a minute moth, as it flits by in bright sunshine or twilight, or a larger one in midnight darkness; to observe traces of insects in a plant, tree, bark or wall crevice, and in the thousand and one other places which conceal them; to stand, too, the bright glare of a summer sun, on burning sand or sparkling sheet of water, and to distinguish at a glance whether or not a captured specimen is worth taking. In his rambles he must often endure besides, fatigue, hunger, thirst, and wet clothes; and at home he will spend many weary, though pleasant hours, in setting out his captures, and arranging his collections. Occasionally, also, a cross-grained farmer, gamekeeper, or "official," will warn him from his hunting ground, sometimes with reason, though more frequently without cause. A host of other annoyances, such as children flocking round him; occasionally vicious bulls or savage dogs, yelping curs, flies, gnats, prickly bushes and thorns, assault him on all sides. On his arrival at home, he should proceed without delay to kill his stock. All moths, except green ones, which do not measure more than one and a half inches, may be smothered with sulphur without much injury. If a number of pill boxes containing specimens, be placed under a glass shade, with the lids slightly raised, and the fumes of half a dozen lucifer matches be allowed to pass into the shade, the moths contained will be ready for setting in the course of half an hour. If removed from the cause of death too soon, many will revive and spoil themselves with fluttering. Chloroform may be used without injury to colour, and is therefore useful in the case of green insects which are spoiled by sulphur. The volatility of chloroform makes it dangerous if used carelessly; and if administered in too strong doses, the moths are made too rigid, and cannot therefore be set. Large insects may be killed either with chloroform or by being pierced under the wing with a sharp spike dipped in a strong solution of oxalic acid. When dead, the specimens may be taken from the boxes and assorted preparatory to setting. Each of those which are good, must have a suitable pin pushed straight through the thorax until a moderate length of it appears on the underside. When all are pinned, arrange them on setting boards suitable in size, and then place the wings in the desired position by means of fine pins, and retain them there till dry, with fine thread or paper. The setting boards should be of various sizes, adapted to the size of the insect, and should be long enough to hold from one to six specimens. They should have an arched surface to impart a graceful curve to the wings, and a groove down the centre to admit the bodies. TENTH ORDINARY MEETING, Held at the ROYAL INSTITUTION, on the 9th of March, 1857, The following gentlemen were elected Ordinary Members :- ROBERT A. MACFIE, WALTER SAUNders, CHRISTOPHER BELL. Dr. Thomson read the following letter from Dr. Livingstone, the African explorer, in reply to the address from the Society (p. 76), and his letter accompanying it : London, 57, Sloane-street, 26th February, 1857. MY DEAR SIR,-I had the honour to receive a very gratifying address from the members of your Society, touching my late discoveries in Africa, at an early period of the present month, and it was accompanied with a very polite request to deliver a lecture to the Society during my passage through Liverpool. I regret that my engagements have been of such a nature as to prevent my returning proper acknowledgements for your very kind and flattering expressions of approbation. I really feel very grateful for the good opinion of such a body of men. Our feelings, however, are somewhat different. They kindly look to the past-I look to the future, and see so much hard work in store before I can think myself entitled to the words "well done," I never become elated. I can thank you, however, for your sympathy, and do so most sincerely. My time is so very limited (and I am no public speaker either) that the only effort I could feel myself ever justified in attempting, would be to address the constituents of the London Missionary Society, many of whom live in your town.-Believe me, sir, most sincerely yours, DAVID LIVINGSTONE. Letters were also read upon the subject of the Austrian Expedition round the World, from Dr. Karl Scherzer to James Yates, Esq., Corresponding Member. Mr. T. C. ARCHER exhibited a very beautiful case of anatomised seed vessels and leaves, prepared by Mr. Hawse, of London, whose beautiful manipulation of these delicate objects is most remarkable. The seed vessels were chiefly those of the campanula, poppy, &c., and the leaves those of the magnolia grandiflora, ivy, and others. They were most tastefully arranged, and interspersed with bleached preparations of Aira caspitosa, Lagurus ovatus, Briza maxima, ferns, lycopodiums, &c., and were presented to the Museum of the Royal Institution. Mr. ARCHER also exhibited a cut flower of the curious aroideous plant, called in North America the skunk flower, Symplocarpus fœtidus, which, from its resemblance to one of the common large dark-coloured cowrie shells, excited some interest. The first paper for the evening was then read, ON THE ADVANTAGES TO BE DERIVED FROM THE ADOPTION OF THE METRICAL TON OF 1000 KILOGRAMMES IN THE MEASUREMENT OF SHIPS. BY JAMES YATES, Esq., F.R.S., F.S.A.* The metrical ton is now recognised, and is now practically adopted by a considerable number of the principal mercantile nations. It is established in France, Belgium, Holland, Prussia, Hamburg, and the other Hanseatic ports, Denmark, the kingdom of Sardinia, Algeria, and several South American States. Its adoption, after a few years, has been decreed by the governments of Spain and Portugal. Besides Great Britain and its dependencies, the only commercial nations of importance which do not already use the metrical ton are the United States of North America, Russia, Sweden, Greece, Turkey, and Egypt. There can be no doubt that these latter countries would adopt it, if Great Britain led the way. The metrical ton being equal to 1000 kilogrammes, while the British ton is nearly 1015, differing only by 1 per cent., it is evident that no objection can arise from the adoption of the former, except the temporary inconvenience which accompanies every change. According to a return issued by the Board of Trade, the exports from the United Kingdom in 1855, consisting of British and Irish produce and manufactures, amounted in value to £95,688,085, or nearly £96,000,000. The countries which use the metrical ton, and are included in this statement of exports, are as follows: Prussia, Hanover, and the Hanseatic Towns ...£9,787,600 This paper was read by the Rev. J. Robberds, the author of the paper being absent through illness. A note from Mr. Yates stated that he had communicated to Rear-Admiral the Earl of Hardwicke, chairman of the Tonnage Registration Committee, and to other members of that committee, his ideas upon the subject, and that they had acknowledged the import his views, thinking that the measurement and registration of ships' perfect until it became international. tonn Thus the portion of these exports sent to countries using the metrical ton may be stated at £28,000,000 nearly. A considerable proportion of the countries to which the remaining £68,000,000 of goods were exported do not use either the English or the metrical ton, but some other weight. So large a proportion of our foreign commerce being already carried on with nations using the metrical ton, it appears highly probable that its adoption by Great Britain would speedily lead to its universal adoption throughout the world. Nor can it be questioned that this would be a most proper adjunct to the recent alteratious of the Navigation Law, by which the ships of all countries are permitted to carry goods to and from Great Britain with unrestricted freedom, and even the ships themselves may be bought and sold like any other description of merchandize. A common method of computing their capacity, and their value would be a manifest and indisputable advantage. Let us now consider what are the recommendations of the metrical ton, independently of its extensive adoption throughout the world. It appears to surpass the English ton in regard to exactness, simplicity, and facility of application. According to the English method, the linear measures are computed in feet, inches, and eighths of an inch; or, if recourse is had to decimals, in feet and hundredths of a foot. For measuring length in vessels of all kinds, the use of a measuring line divided into metres and centimetres appears simple, easy, and commodious in the extreme. But the chief advantage of the metrical ton will be apparent on considering the linear measure as the basis employed for the cubage of vessels, and the deduction of the tonnage therefrom. According to the old English method, the length, breadth, and height, are in every case multiplied into one another, being expressed either in feet and inches, or in feet and 100ths of a foot, and the product being the estimated capacity of the vessel in cubic feet, is divided by thirty-five, because a ton of water is supposed to measure thirty-five cubic feet. Thus the number of tons which the vessel can carry is obtained, not, however, with exactness, because the ratio of thirty-five cubic feet to a ton of water is only a rude approximation. If the other method be adopted, it will only be necessary to multiply into one another the length, breadth, and height expressed in metres and centimetres, and the product will give the tonnage without any further trouble and with perfect exactness, because a metrical ton is the weight of a cubic metre of water. This remarkable facility is obtained through the care taken, in constructing the metrical system, to adjust the weights, so that they |