through five editions in a very short time-each edition containing a large amount of new matter. The work, by these numerous additions, became so changed in character, that he reconstructed it, and brought out a new work called "Elements of Geology," and greatly altered his "Principles" as regards arrangements. In the latter, he presented explanations of the various forces at work in the earth and in the universe likely to affect the earth. In the former, he described the observed effects. Subsequently he brought out the "Student's Manual of Geology," in which he brought together most of the facts mentioned in the two previous works.

No geologist before Lyell's time had devoted himself so exclusively and so laboriously to the science. He not only kept himself acquainted with the discoveries made by others, but he travelled over large portions of the earth's surface, with the view of verifying alleged facts, and making di coveries himself.

He went to Norway, Sweden, Belgium, Switzerland, Germany, Spain, Catalonia, and the Danish islands of Seeland and Monen. He was twice in America. On the first occasion, in 1841, he went, in compliance with an invitation, to deliver a course of lectures at Boston. He then remained in the New World a whole year, his explorations extending from Canada through the States to the mouths of the Mississippi. On returning to England, he published his "Travels in North America," in which, whilst geological information chiefly is given, some useful views occur on other subjects also. In 1845 he paid a second visit to America, and examined more particularly the Southern States and the coasts bordering the Gulf of Mexico. On his return to England, he published his "Second Visit to the United States,”—a companion to his former work.

The most recent of Lyell's important works was his "Antiquity of Man," which went through four editions, the first having come out in 1863, the last in 1873. But beside these elaborate works, he published numerous memoirs, most of which had been read at meetings of the Geological Society and British Association for the Advancement of Science.

In 1836, and also in 1850, he was President of the London Geological Society. The Royal Society's Copley Medal was awarded

to him in 1858, and the Geological Society's Wollaston Medal was awarded to him in 1866.

In the year 1864 he presided at the Bath Meeting of the British Association for the Advancement of Science. He was Patron of the Scotch Geological Society. In the year 1848 he was knighted, and in the year 1864 he received a baronetcy in recognition of his services to science.

Sir Charles Lyell was married in 1832 to Mary Elizabeth, eldest daughter of the late Leonard Horner, himself a distinguished geologist. Lady Lyell was a devoted wife, and sympathised with her husband in his pursuits, accompanying him in all his travels, and assisting him in literary work.

During the last five or six years, Sir Charles Lyell lost his eyesight to such an extent that he could neither read nor recognise his friends. The last time that I was in his house, Harley Street, London, Lady Lyell had to lead him, and make known to him the presence of several friends who came in.

Lady Lyell's death in the year 1874 was a severe shock to her husband. After that event, Sir Charles's health rapidly failed. His death was caused by a severe fall on the staircase of his house, he having, owing to his blindness, missed the uppermost step.

Probably few men were ever so devoted to any special object, as Sir Charles Lyell was to geology, through his whole life. He was inspired by a genuine love of truth, and for its sake did not hesitate to retract opinions when he found he was mistaken. In the three first editions of his "Antiquity of Man" he had expressed his concurrence in the opinion of some Scotch geologists, that the land near the Firth of Forth had risen 25 feet since the Roman occupation. In the last edition of the work, he revoked that concurrence. In the account given by him of the Glen Roy terraces, he published his belief, that they were due to fresh water lakes. In a letter which I received from him shortly before his death, adverting to some facts recently discovered, he allows, that perhaps after all, Darwin's theory of the terrace having been made by the sea, might prove to be correct. Sir Charles Lyell in this respect showed an example to all men of science, in caring more for the interests of truth, than for mere consistency.

WILLIAM EDMOND LOGAN, another Honorary Fellow of the Society, was born at Montreal, Canada, in the year 1798, and died on 22d June 1875.

His father was originally a landed proprietor in Stirlingshire, and emigrated to Canada. He sent his son from Canada, when very young, to Scotland, to be educated in the High School, and afterwards in the University of Edinburgh.

When young Logan was in Edinburgh, geological investigations and speculations were exciting much interest, in consequence of the discussion between the Huttonians and Wernerians. Mr Logan then acquired a taste for geology; and having occasion to go to South Wales, he began to study the rocks in the coal-fields there, at this time, beginning to be more extensively worked. Having procured an Ordnance Survey map on a large scale, he was at the trouble to trace out and lay down upon it the outcrop of all the coal seams worked through extensive tracts of country. Seeing where the outcrops ceased to be continuous, he ascertained the amount and direction of the dykes and slips by which the strata had been dislocated. He descended into the mines, and studied for himself the structure of the coal, and examined particularly the fossils found in the coal. He was then struck by the fact, that every coal seam lay upon a bed of blue-coloured clay, in which apparently the plants had grown, now found petrified in coal. In several instances he discovered that some of the fossil trees which had their trunks in the coal-bed had their roots still stretching into the underlying bed of clay.

About this time Sir Henry de la Beche, who was directing the Geological Survey of England and Wales, happened to come into South Wales. Having heard of Mr Logan, he became acquainted with him; and having seen the work he had been carrying on, he at once put him on the staff of the survey.

Mr Logan having permanently adopted geology as a profession, became a Member of the Geological Society of London. Frequently joining in the discussions there, he made the acquaintance of Sir Charles Lyell, Sir Roderick Murchison, and other leading geologists. Having obtained leave of absence to visit his father in Canada, he went there in 1841, and spent much of his time in exploring the great coal-fields of Nova Scotia and Pennsylvania.

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In the spring of 1842 he returned to England, and in the Geological Society gave an interesting account of his survey in these American coal-fields. He had been particularly anxious to obtain a confirmation of his discovery, that coal seams everywhere rested on fire-clay; and he was able to afford these proofs from what he had seen in Nova Scotia.

He had made another discovery in these coal-fields. He had discovered the footprints of a reptile; and he brought to London with him the sandstone slab which contained these prints. This slab was submitted to Professor Owen, who expressed a clear opinion, that the impressions had been made by an animal which had four claws on the two fore feet, and three claws on the hind feet. The interest attaching to this discovery was, that no reptile had been discovered in rocks so old, it being at the bottom of the Carboniferous formation;-whereas, previously, no reptiles had been found below the Permian rocks.

I mention this discovery of Logan's, because I see that my friend Principal Dawson of Montreal, in his "Book on Acadian Geology," mentions that discoveries of similar reptiles, made in the year 1844 in Sweden and the United States, had been asserted to be prior to others of the same kind.

Logan's reputation as a geologist was now established. It led to his being entrusted with the charge of the Canadian Geological Survey, on the recommendation of Sir Roderick Murchison and Sir Henry de la Beche. The Canadian Legislature had wisely resolved to have the mineral riches of the country ascertained by competent surveyers. For nearly thirty years Sir William conducted the Canadian Survey, and drew most important conclusions regarding the whole series of rocks in that part of the world-conclusions universally accepted by geologists as correct.

At the Paris International Exhibition of 1855, he showed a large collection of specimens, besides magnificent maps and diagrams, which attained much attention, and received great commendation. It was on this occasion, that the British Government, in recognition of his eminence as a geologist, and of his services in Canada, bestowed on him the honour of knighthood.

Sir William did not publish anything beyond the official reports of his survey. He was not ambitious of fame, either as an author

or otherwise. He stuck closely to the work he had undertaken, and continued at it till the year 1869, when failing health led him to resign.

He, however, continued to take an interest in geological pursuits, and gave, from his private funds, a donation of L.5000, for the endowment of a chair of geology in the M'Gill College, Montreal.

CHARLES WHEATSTONE was born at Gloucester in 1802, and died in Paris 19th October 1875. He was on the list of our British Honorary Fellows.

The rudiments of education were obtained by him at a private school. Whether he afterwards went to a university, I have not discovered.

His youth and early manhood were devoted to the construction of musical instruments, and to experiments with the view of discovering more exactly the laws of sound. He paid special attention to the instruments depending on vibrating springs. The present improved Concertina is due to his invention.

His first scientific memoir was in the year 1823, when he published in the "Philosophical Annals" an account of some "New Experiments on Sound." It excited considerable attention among physicists, and was translated into several foreign periodicals. In 1827, in the "Quarterly Journal of Science," he published farther Experiments on Audition," accompanied by a description of the Kaleidophone, an instrument to illustrate both acoustical and optical phenomena.

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During the next eleven years, he continued to produce papers und to invent instruments for illustrating the properties of sound.

In 1838 he seems to have entered on a different subject of investigation altogether, viz., light. He had discovered relations between waves of sound and waves of light. He communicated to the Royal Society of London, and also to the British Association, an account of some hitherto unobserved phenomena of binocular vision, illustrating them by means of the instrument which he invented, called the "Stereoscope." To Wheatstone is due the discovery, that the conception of solidity is due entirely to the mental union of two dissimilar perspectives.

In 1852 he invented an instrument called the "Pseudoscope,"