A cable dispatch from London reports the death in that city of Thomas Graham, the celebrated chemist and Master of the Mint. He was born in Glasgow, Scotland, on the 21st of December, 1805his father being a merchant and manufacturer in that city. Mr. Graham was educated at Glasgow School, and subsequently at the University of Glasgow,where he graduated, taking the degree of M.A., in 1826. He then moved to Edinburgh, but at the end of two years,returned to his native place and established a laboratory for the practical study of chemistry. He also lectured at the Mechanics Institute, and was elected Andersonian Professor at Glasgow. This office he held until 1837, when he resigned for the purpose of accepting the Professorship of Chemistry in the London University, to which he had been appointed. In 1855 Sir John Herschel retired from the Mastership of the Mint, and Mr. Graham was appointed to fill the vacancy, holding the position with credit until his death. There has probably been no chemist in Great Britain of equal ability to Mr. Graham during the past quarter of a century. His study of the sciences was complete, and his discoveries and works have been of great scientific importance to the world. His most remarkable discoveries were the law pf the diffusion of gases, the diffusion of liquids,and the new method of separation known as dialysis. For the first named discovery he received the Kieth prize of the Royal Society of Edinburgh in 1834, and for the last, the Copley medal of the Royal Society in 1862. Ofhis literary productions, the most important and best known.is »Elements of Chemistv,»which has been extensively circulated and read in Great Britain and Germany, and is also a familial- work to scientific students in the United States and other parts of the world. Mr . Graham was el ecte d a Fellow of the Royal Society in 1836, a corresponding member of the Academy of Sciences of the Institute of Fran.; in 1848, and was created an honorary D.C.L. by Oxford University in 1855. The readers of the Scientific American will remem b er the account given on page 244, of our last volume, of the discoveries made by Mr. Graham respecting the properties of hydrogen. Gas for Lighthouses. A series of letters and reports sent to th e Commissioners of Lighthouses and the Board of Trade has resulted in a request being made to Professor Tyndall, by the latter body, that he would report upon the proposal to substitute gas for oil as an illuminating power for lighthouses, as illustrated in the lighthouses of Howth Baily and Wicklow Head. Various experiments were made at Howth Baily, and Professor Tyndall says that the superiority of the gas over the oil flame is rendered very conspicuous by these experiments. The 28-jet burner possesses 2t times, the 48-jet burner 4J times, the 68-jet burner 7! times, the 88-jet burner 9il- times, and the lOS-jet burner 13 times the illuminating power of the four-wick flame. The oil lamp with which the gas flame was compared was the most perfect one employed by the Commissioners of Irish Lights. Further experiments were also made, and it appeared that the whole of the gas-lighting apparatus was entirely under the control of the keeper, and that no damage was likely to arise from it. The 28-jet gas burner, when seen from a position some miles off, appeared to be very nearly upon an equality with the oil lamps, but when muffled to represent a fog it had a slight advantage. Of course with the brighter jet burners a great improvement was apparent, and before the 1 08-jet burner the oil lamp grew quite pale. By the adoption of a system of gas lighting a great saving in cost would be effected ; but such a system would not be possible on rock lighthouses. Professor Tyndall recommends the encouragement of this system of illumination in Ireland. To kill cockroaches take carbolic acid and powdered camphor in equal parts; put them in a bottle ; they v; ill become fluid. With a painters brush of the size called a sash tool, put the mixture on the cracks or places where the » critters » hide; they will come out at once. It is wonderful to see the heroism with which they move to certain death. Nothing more sublime in history; the extirpation is certain and complete. While on this theme I would add that a mixture of carbolic acid with waterone-fourth acid three-fourths water -put on 1\ dog, will kill fleas at once. I have seen it tried. G. W. B. 1869 SCIENTIFIC AMERICAN, INC. October 9, 1869.] 2-31 Darwinism and Design. (hom the Student.) Darwinism is only one of several branches of a kind of philosophy long known to students of the historical developments of human thought. The Darwinian apparatus consists in a multitude of facts collected from an immense field of research, and pointing to particular methods by which hereditary changes in the organic world may lead to the preservation or extinction of particular forms. That offspring sometimes vary from the parent type is beyond dispute; that such variations are sometimes hereditary, is equally beyond dispute, nor can any one deny that when a modification arises which gives a group of creatures more power to fight their battle of life, they will be benefited thereby, and may multiply and flourish in situations where creatures not so modified would die out. The extent to which Darwins » Natural Selection» is sufficient to account for.the changes that have occurred, is open to question. Laws and principles of which we have as yet no cognizance, may assume an importance we are not prepared for; but no fresh discovery can invalidate the facts on which Darwin and his followers rely. No one who has weeded a garden can doubt the reality of the »battle of life » which he portrays, and no one who has watched insects attacking plants, birds assailing insects, and climate with its fluctuations, frequently fighting against all, can doubt that the natural world does present a scene of struggle, in which the strongest and the best protected prevail, while the weaker and less protected have to give way. Of course, such terms as » strong » and » weak » must be understood in a wide sensea delicately-organized plant, for example, may be characterized by the former epithet, when compared with a much more robust vegetable, if it surpasses the latter in power of extracting nutriment from a particular soil, or in withstanding prolonged drought, excess of moisture, or extremes of temperature. But the natural world is not made up of contention and strife any more than those elements constitute the sum of human society. Natural adaptations of the most varied and wonderful kinds abound, none being more remarkable than those which the Darwinians adduce. What can be more amazing than the dependence of a flower upon an insect, so that the butterfly, moth, or humble bee is made the carrier of pollen from one corolla to another, and an animal thus provides for the perpetuation of a vegetable race. What savors more of design than the » mimicry » which has been frequently illustrated in our pages, a plan by which a defenseless creature assumes the aspect of a strong one, a delicate creature the appearance of a tough one, or a butterfly when perching on a twig be-comes indistinguishable from a dead leaf, and in each case enemies are deceived, and security obtained ? If a new writer desired to compile the most elaborate and convincing series of design arguments, he would have recourse to the Darwinian armory for the most striking of recently ascertained facts. Why, then, is Darwinism in many quarters contrasted with and opposed to design ? The answer may be found in the defects of the older forms oi the design argument, rather than in any conclusion that logically follows from Darwinian speculations. Many of the older comparative anatomists contented themselves with regarding animal or vegetable organization simply from what is called the teleological point of view. They saw, or fancied they saw, the final cause, or reason why, everything was done. They collected together a great mass of information concerning special adaptations, and it was assumed that no organ, or portion of an animal, not de-formed, was without its special use to that particular creature; but plain and palpable facts did not s ustain the universal application of this theory. Animals were found with rudimentary partsbones, for example, which, if developed, might have supported a kangaroo-like pouchto which no function could be assigned, and in these cases, which are very numerous, the doctrine of special application broke down. Then came theories of »types,» and if anything appeared in a creature that was not of any use to it, the explanation was that the creature in quest ion belonged to a group all formed according to »type,» and the rudimentary, or useless part, was put in to make it conform to the typical idea, something like the procedure of the old gardener, who had a particular » type» of uniformity so strongly in his mind, that, having put a naughty boy in one corner, he put a good boy in the opposite one not to damage the design. Further knowledge left the »types» high and dry on the shores of metaphysical abstraction, and introduced the notion of descent with variations, according to which the occurrence of non-essential, useless, or rudimentary points admits of easy explanation. That certain animals see because theY have eyes, and that birds fly because they have wings, are statements not inconsistent with tlie doctrines of final causes, though it is easy to place them in opposition to the common assertion that the animals in question were endowed with eyes in order that they might see, and that the birds were gifted with wings in order that they might fly. To perfect the design argument when it is applied to elucidate a system of descent with modifications, struggles with life conditions, and the survival of the fittest, we have to show reasons for believing that the changes which occur in the organic world, follow a law, or set of laws, indicative of intelligence, and capable of working out beneficial results. At present, the physiological laws which determine the condition under which offspring faithfully transmit or depart from the peculiarities of the parental type are unknown, and it is only a very small portion of the natural plan that comes within cognizance. So that we cannot expect to have clear information as to either purposes or conclusion!. Darwin observes, » however much we may wish it, we cannot blindly follow Professor Asa Grey in his belief, that variation has been led along certain beneficial lines like a stream along definite and useful lines of irrigation. If we assume that each particular variation was from the beginning of all time preordained, the plasticity of organization which leads to many injurious deviations of structure, as well as that redundant power of reproduction which invariably leads to a struggle for existence, and as a consequence to the selection or survival of the fittest, must appear to us superfluous laws of nature.» We cited this passage and remarked upon it when it was first published in Mr. Darwins » Plants and Animals under Domestication.» His argument simply reminds us of a diffi-calty not at all peculiar to natural history or physiology, but which encounters us in all directions. Evidently it is not the design of nature to reach what we call good ends, without what look like breaks, interruptions, and failures. If speculations on the modifications of organic beings according to the principles of Mr. Darwin, bring us into contact with many fresh puzzles and perplexities of this description. they also supply a fresh store of facts, which tend to increase our belief that the system is con form able to our religious instincts and moral nature. No natural theologian can affirm that any theory yet propounded, supplies a satisfactory explanation of all the moral difficulties, or intellectual difficulties which stand in the way or a perfect comprehension of the character of the great plan. Why it is obviously benevolent in a thousand directions, and apparently harsh in a thousand others, we do not know, any more from Darwin than we did from Paley, but we certainly are not left in a denser mist; and as modern researches have enabled us to catch glimpses of a far wider, more complicated, and comprehensive plan than the older thinkers had any conception of, we may, while lamenting the limitations of our mental vision, take comfort in the belief that in the vast regions of the yet unknown, there lie ample satisfaction for all our hopes, and ample resolution of all our doubt. How to Preserve Pencil Drawings. An ingenious means of effecting this has been invented by M. E. Rouget, of Paris. This invention consists in obtaining the fixation of such drawings, tracings, or sketches, by directly projecting on these latter any suitable adhesive liquid reduced ty a fine spray, or in wh at is commonly called the atomized or pulverized state, by causing the liquid to pass rapidly under pressure through one or more capilliary tubes or openings. By this method the defects of the transudation process are entirely done away with, besides which the operation is executed in less time, and may be performed at once by the artist without the slightest difficulty. As for the fLx-ation liquid, any colorless, or nearly colorless, liquid which allows of being atomized, and which, after becoming dry, causes the particles of the charcoal, or other drawing materials made use of, to adhere sufficiently firmly to the paper or other drawing surface, may serve for the purpose. Thus. for iristance, a liquid, which has given the patentee the most satisfactory results, is obtained by adding to a solution of three ounces of white s ugar candy and two ounces of white shellac in about two pints of spirits of wine, a decoction of about one ounce of fucus crispus in one pint of distilled water. Extraordinary Phenomenon, On the evening ofthe 30th May the inhabitants of Greiffen-berg, Germany, and the neighboring villages, for more than a German mile in circuit, were the witnesses of an extraordinary natural phenomenon. Between hine and ten oclock thunder clouds seemed to he gathering around the Iser and Risengebirge, to the south, while the rest of the sky appeared to be covered only by light clouds. Now and then a few flashes of lightning were seen in the far distance. Suddenly all eyes were blinded by a fall of fire, differing both in form and color from common lightning, which was followed in four or five seconds by a deep and terrific report, like a loud peal of thunder. All the windows rattled and the houses seemed shaken to their foundations. Those who were in the open air say that they seemed to be wrapped in fire and deprived of air some instants. A mild and moderate rain, without thunder or lightning, followed. Opinions differ as to whether the above appearances are to be attributed to a meteor or to a sudden discharge of electricity. gestion before it can enter the tissues of the body, and form the new blood requisite to sustain life. Pepsine can be artificially extracted from the stomach of a recently killed animal, that of a pig or cal f in particular, and when it is placed in contact with minced-up boiled egg, butchers meat, etc., in a glass vessel, it dissolves the meat apparently in tbe same way as it does in the living stomach. Substances which are occasionally taken into the stomach, such as the stones of fruit, the rind of raisins, or Orleans plums, are unacted upon by pepsine; hence such substances are truly said to be indigestible. Physicians often administer pepsine in cases where indigestion of the ordinary food occurs, and in many cases with marked benefit. The inordinate use of tobacco, ardent spirits, and condiments, arrests the flow of the gastric juice ; hence the evils resulting from it. The preparation sold by most druggists, under the name of pepsine, consists of dried and powdered glandular layers of the stomachs of pigs or calves.S. Piesse.