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Prof. R. K. DOUGLAS, Professor of Chinese, King's College, London. Three Lectures on "Modern Society in China." On Tuesdays, May 2, 9, 16. Half-a Guinea.

E. L. S. HORSBURGH, Esq., M.A. Three Lectures on "The Waterloo Campaign." On Tuesdays, May 23, 30; June 6. Half-a-Guinea.

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R. BOWDLER SHARPE, Esq., LL.D., Zoological Department, British Museum. Four Lectures on "The Geographical Distribution of Birds." On Thursdays, May 18, 25: June 1, 8. Half-a-Guinea.


JAMES SWINBURNE, Esq., M. Inst. E. E. Three Lectures on Some Applications of Electricity to Chemistry" (the Tyndall Lectures). Saturdays, April 15, 22, 29. Half-a-Guinea.

HENRY CRAIK, Esq., C. B., LL.D. Three Lectures on (1) Johnson and Milton"; (2) "Johnson and Swift" (3) "Johnson and Wesley." On Saturdays, May 6, 13, 20. Half-a-Guinea.

A. C. MACKENZIE, Esq., Mus. Doc., Principal of the Royal Academy of Music. Three Lectures on " Falstaff," a Lyric Comedy, by Boito and Verdi (with Musical Illustrations, by kind permission of the composer and publishers, Messrs. Ricordi, specially granted for these lectures). On Saturdays, May 27: June 3, 10. Half-a-Guinea.

Subscription (to Non-Members) to all the Courses during the Season, Two Guineas. Tickets issued daily.

Members may purchase not less than Three Single Lecture Tickets, available for any Lecture, for Half-a-Guinea.

The FRIDAY EVENING MEETINGS will be resumed on APRIL 14, when Sir WILLIAM H. FLOWER, K.C. B., F. R.S., will give a Discourse on SEALS, at 9 p. m. Succeeding Discourses will probably be given by Prof. A. B. W. KENNEDY, Prof. FRANCIS GOTCH, Mr. SHELFORD BIDWELL, the Right Hon. Lord KELVIN, Mr. ALFRED AUSTIN, Mr. BEERBOHM TREE, Prof. OSBORNE REYNOLDS, Prof T. E. THORPE, and other gentlemen. To these Meetings Members and their Friends only are admitted.

Persons desirous of becoming Members are requested to apply to the SECRETARY. When proposed they are immediately admitted to all the Lectures, to the Friday Evening Meetings, and to the Library and Reading Rooms; and their Families are admitted to the Lectures at a reduced charge. Payment: First Year, Ten Guineas; afterwards, Five Guineas a Year; or a composition of Sixty Guineas.







Telegrams-" Tunzelmann, London."

The Complete Courses qualify Students for entry into Electrical or other Engineering Works.

The First Year's Course is arranged to qualify Students for entering Cooper's Hill, the Central Institution Engineering College, or the Royal School of Mines.

Forty-one Students have entered these Institutions during the last three years, and two Entrance Scholarships have been obtained at the Central Institution.

The College is provided with very complete Laboratories and Dynamoroom, and also with an extensive Geological Collection for the Preliminary Courses for Civil and Mining Engineering Students.

Students are regularly sent to the College by Leading Engineers and Scientific Authorities, whose Names are given in the Prospectus.


The Institute's Examinations in Technology will be held on APRIL 29, and on MAY 3, 6, 8, 10, 13, 26, and 27, and in MANUAL TRAINING on Candidates in Technology not attending any JUNE 3. 7, 8, and 1o. registered Class should apply to the Secretary of the nearest Science Centre. Forms of application for Examination in Technology are now ready, and can be obtained by Local and School Secretari-s from the EXAMINATIONS DEPARTMENT of the City and Guilds Institute, Exhibition Road, S W.


The SUMMER SESSION commences on MAY 1, and Students ther entering are eligible for the Open Scholarships offered for Competition c September 26 and the two following days.

The Hospital contains 695 Beds, of which 500 are in constant occupation The House Physiciancies, House Surgeoncies, Dresserships, and all other Appointments, are given according to the merits of the Candidates, and without extra payment.

Scholarships and Prizes amounting in the aggregate to £550, are open for competition to all students. Special Classes are held for the Examinations of the University of London.

Four Entrance Scholarships, Two Open Scholarships in Classics, Mathe matics, and Modern Languages; one of the value of £100. open to Canci dates under twenty years of age; and one of the value of £50, open to Cand. dates under 25 years of age. Two open Scholarships in Chemistry. Physics, and Biology: one of the value of £150, and another of £60, open to candi dates under 25 years of age.

For Prospectus and further information apply to the Dean, Dr. L. E SHAW, Guy's Hospital, London, S E.


The Technical Instruction Committee for Handsworth, in the County of Stafford, are desirous of receiving applications for the appointment of Head Master of the Art Department of the Handsworth Technical School. Salary (to commence with) £250 per annum.

Applicants must be thoroughly competent to give instruction in the groups of subjects numbered I. to VI. in the regulations of the Department Science and Art, although not holding all the certificates for these groups, and to conduct the School in accordance with the revised regulations of the Department.

Applications accompanied by three original Testimonials stating qual écations and experience, must be sent to me by Post to my Office, Church Street, West Bromwich, on or before MONDAY, the 27th instant.

The Committee, after considering the applications, will, by letter, request the attendance of such Candidates as they may select, and pay their railway fares. (By Order) H. WARD, Hon. Secretary.

West Bromwich, March 15, 1893.


The Committee invites applications for the post of HEAD MASTER È the above school.

The Stipend will be £150, with a Capitation, and one-third of the Gover ment Grant, the Committee guaranteeing for the first year a minimum total of £250.

All particulars will be furnished on request.

Applications, stating Qualifications, and enclosing Eight Copies of Tesu monials, should reach the undersigned not later than MARCH 30, 1893. LOUIS W. MONTAGNON, Hon. Sec.

6 Wellington Square, Cheltenham. UNIVERSITY COLLEGE, LONDON.


The SUMMER SESSION begins on MAY 1. The work is arranged so that a Student may advantageously begin the Science part of the Medical Curriculum then. Full information may be obtained from either of the undersigned. E. A. SCHÄFER, F. R.S., Dean of the Faculty. J. M. HORSBURGH, M.A., Secretary.

A Fine 4-inch Refracting TELESCOPE, by COOKE, of York, with Silver Circles, the usual Eyepieces, &c., and some Valuable Additions, nearly equal new, and which cost about go, offered for 50 Guineas. Also the OBSERVATORY (14 miles from London), not 3 years old, first-rate condition, for £15.-F.RAS," Banstead, Surrey.

A Fine Binocular Microscope (Largest) by Ross, with Apparatus and High-class Objectives from 2 inch to Objects fitted in Cabinets, &c. Cost nearly £200. To be sold chea Equal to new-HUGHES, Brewster House, Mortimer Road, King land, N.

To Collectors and Buyers of Precious and

Fancy Stones.-R. C. NOCKOLD, Diamond and Oriental Stone Mr chant, 12 Frith Street, Soho, W., has a very large assortment of Spec men Stones, cut and uncut. Fine Collection of Coloured Diamonds and in Matrix. Inspection invited.

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Sale by Auction.



MR. J. C. STEVENS will Sell by Auction at his Great Rooms, 38 King Street, Covent Garden. on l'UESDAY, MARCH 28, at 12 30 precisely, Natural History Specimens, comprising:-Small Collection of British Lepidoptera, Exotic and British Coleoptera, Insects in Papers, Cabinets, Animal Skins, Heads and Horns of Animals, Birds' Eggs and Skins, Shells, Minerals, Corals, Curios, &c.

On View day prior, 10 till 4, and Morning of Sale, and Catalogues had.



97 REGENT STREET, LONDON, W. ESTABLISHED 1840. Late 277 STRAND Choice Mineral Specimens, Gem Stones, Carved Opals, Polished Agates, Rock Crystal Balls, Fossils, Rocks, and Rock Sections.


Mr. HENSON has just received some good Groups of Japanese Stibnite, interesting Quartz Crystals inclosing Rutile and other Substances, and a Very Fine Rock Crystal Ball, 4 inches diameter, perfectly free from flaws, small Crystal Balls, with inclosures, Rock Crystal Carvings &c., &c.; Crystallised Hydrargillite, Bertrandite, Polvbasite, Diamonds, Chalcotrichite, Arizona, Yellow Terminated Beryls, Geikielite, and Yttrotantalite. Diatomaceous Earth from Hakodati, Japan.


Lecturers, Museums, &c.

Museum Fittings, Cases, and all Materials for Display, &c., of
Elementary Works. All greatly improved.

NEW LISTS NOW READY. And may be had post free on application at the Repository and Museum, 88 CHARLOTTE ST., FITZROY SQUARE, LONDON.

F. H. BUTLER, M.A. Oxon., Assoc. R. S. Mines.


158 BROMPTON ROAD, LONDON. Dealer in Rocks, Minerals, Fossils, and other Objects of Scientific Interest.

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Collections of Rocks. Minerals, Fossils, or Recent Shells furnished in accordance with special requirements. SCHOOL COLLECTIONS of Sedimentary and Igneous Rocks, 15 specimens of fair size in case with divisions, Rabbits and other objects for Biological Study supplied. Card-Trays and Glass-topped Boxes of any required dimensions made promptly to order. Sections of Shells and general Lapidary's Work executed. Micro-Rock Slides New to Stock-Schistose, Elæ lite, Syenite, Norway: Dolerite, Rowley; Porphyritic Pitchstone, Beinn Shiant; and Sanidine Trachyte, Gleichenberg.


For the Use of Students, Science Teachers, Prospectors, &c., and to illustrate the leading Text-books, in Boxes, with Trays.

50 Specimens, 10s. 6d.; 100 do., 21s.; 200 do., 42s New Price List of Minerals, Rocks, and Stratigraphical Series of Fossils Post Free.

ROCK SECTIONS for the MICROSCOPE from 1s. 6d. each, Post Free CATALOGUES GRATIS.







180 ST. GEORGE STREET EAST. Implements of Savage Warfare, Idols, Sacred Masks, Peruvian Pottery, Netsukis, China, Lacquer, Gongs, Shells, and other Curios.


Volvox globator, Epistylis flavicans, Stentor cæruleus, Spongilla fluviatilis, Rhinops vitrea, Lophopus crystallinus, and other objects Amaba, Hydra, Spirogyra, and other types (Animal and Vegetable) for Students. Specimen Tube, with Drawing and Description. One Shilling, Post Free. T. E. BOLTON,



Soreness and Dryness, Tickling and Irritation, inducing Cough, and affecting the Voice. For these symptoms use


In contact with the glands at the moment they are excited by the act of sucking, the Glycerine in these agreeable Confections becomes actively healing.

Sold only in Boxes, 74d., and Tins, 1s. 1d., Labelled. JAMES EPPS & CO., Homœopathic Chemists, LONDON.



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the chief Agricultural Journal in Scotland, circulates extensively among Landowners, Farmers, Resident Agents, and others interested in the management of land throughout the United Kingdom.

The AGRICULTURIST is published every Wednesday afternoon in time for the Evening Mails, and contains Reports of all the principal British and Irish Markets of the week.

The special attention of Land Agents is directed to the AGRICUL TURIST as one of the best existing Papers for Advertising Farms to be Let and Estates for Sale.

Advertisers addressing themselves to Farmers will find the AGRICUL.. TURIST a first-class medium for reaching that Class.

Price 3d. By Post 3d. Annual Subscription, payable in advance, 145. Offices-377 High Street, Edinburgh, and 145 Queen Victoria Street, London, E.C. Money Orders payable to C. and R. ANDERSON.

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This Magazine, commenced in 1864, contains standard articles and notes on all subjects connected with Entomology, and especially on the Insects of the British Isles.

Subscription-Six Shillings per Annum, post free.

London: GURNEY & JACKSON (Mr. Van Voorst's Successors).
I Paternoster Row.

N. B.-A Second Series was commenced with the Number for January, 1890.

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TRANSACTIONS OF THE ROYAL IRISH ACA. DEMY. Vols. XVII. 3 parts; XVIII., part 1; XIX.. part 2; XXII. (Polite Literature). 4 parts; XXIV., 37 Parts; XXV. (Science), parts 1-3, 5-20; XXVI. (Science), parts 1-13, 17 to 22; XXVII., 8 parts. 1833-86. 50s.

MEMOIRS of ROYAL ASTRONOMICAL SOCIETY OF LONDON, Vols. 36 (1866-7) to 46 (1880-1). 13 parts, 4to. 42s. BOLOGNA. De Bononiensi, Scientiarum et Artium Institutio atque Academia commentarii. 7 Vols. in 10. 4to, half vellum.

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NEW AND SCIENTIFIC BOOKS. COMPARATIVE GEOLOGY: Text-Book of. By Dr. KAYSER (Marburg), edited by PHILIP LAKE, M.A F.GS, late Harkness Scholar in the University of Cambridge. Wit 73 Plates and 70 Figures in the Text. 8vo. 18s. [This day. The Publishers have some confidence in claiming that this is the T ILLUSTRATED geological text-book yet produced in Great Britain. BIOLOGY: Text-Book of Elementary. Adapted for the Use of Students for the Examination presented by the Conjoint Board of the Royal Colleges of Physicians and Surgeons. B H. J. CAMPBELL, M.D., Senior Demonstrator of Biology in Guy's Hospital. 136 Cuts. 6s.



Text-book of. By Dr. E. STRASBURGER. Third English Edition by Professor W. HILLHOUSE. 149 Cuts. 95. This day. EMBRYOLOGY OF MAN AND MAMMALS: Text-book of. By Dr. OSCAR HERTWIG (Berlin). Translated by E. L. MARK, Ph.D. With 339 Figures in the Text, and 2 Coloured Plates. 8vo. 215.

To be quickly followed by an English edition of Professors KoRSCHELT and HEIDER'S "Invertebrate Embryology."



DISEASE IN GREAT BRITAIN. By Dr. ALFRED HAVI LAND. With 8 Coloured Maps. Royal 8vo, 15s. PHYSIOLOGICAL PSYCHOLOGY: Introduction to. By Dr. TH. ZIEHEN (Jena) Translated by C. C VAN LIEW and Dr. OTTO BEYER. With 21 Illustrations. "We want such a book badly. We can recommend Ziehen as erond ingly well adapted to give the student a clear idea of the scope, and the methods of the new science of physiological psychol gy."-Nature. PETROLOGY: Text-Book of. A Descrip

tion of the Rock-forming Minerals and a Synopsis of the Chief Types Igneous Rocks. By F. H. HATCH, Ph.D., F.G.S., of the Geologica Survey of U. K. With 86 Cuts. 75. 6d.

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Thirteenth Edition, en irely Re-written by WM. FREAM, LL.D., Steven Lecturer in the University of Edinburgh, Author of "The Elements of Agriculture," &c.

"Dr. Fream is to be congratulated on the successful attempt he has made to give us a work which will at once become the standard classic of the farm practice of the country "-Times. February 13, 1893.

"Dr. Fream's new volume ought to be in every farm, and in the library of every land-owner."-Mark Lane Express, February 13.1893

"It will fully sustain and even enhance the pre-eminent reputation Dr. Fream has won as an agricultural author. In every respect the work is new and thoroughly up to date."-North British Agriculturist, February 21, 1893.


Edited by F. H. WEBB, Secretary.

Part CIII.

Containing a full Report of the continuation of the discussion on Prof. J. A. Fleming's Paper, "EXPERIMENTAL RESEARCHES ON ALTER VAIE CURRENT TRANSFORMERS," and the Inaugural Address of the new President, Mr. W. H. Preece, F.R.S.

Price Two Shillings.

Messrs. E. & F. N. SPON, 125 Strand.




Newest Publications sent for Selection.

French Academy Pictures, Classical Figures. Statuary, Portraits, Views Artists' Life Studies, &c. All usual sizes from C. D V. to 30 x 24 inches Prices from 2d. to 215. each. Address: ERDMANN and SCHANZ (N. 67). Photographic Publishers, Clapham Junction, London (Establishe 1876). No obligation to Purchase. Please write for Catalogue free t



COLLIERS AND COLLIERY EXPLOSIONS. Coal Pits and Pitmen. A Short History of the Coal Trade, and the Legislation affecting it. By R. Nelson Boyd, M. Inst.C.E. (London: Whittaker and Co.)


S the author remarks in his preface, his present work is a re-cast of a book published for him in 1879 by W. H. Allen and Co., under the title of "Coal Mines' Inspection." A casual examination of both books shows that they are alike in their main features; only, the latter work has been extended so as to include some of the events of later years. The subject is divided into twelve chapters, to which are added four short appendices and a good index. The text extends to 239 pages Svo of good readable print, and there are a few good illustrations of ancient mechanical arrangements, including the steel mill.

Mr. Boyd begins by giving a very short historical account of the situation before Parliament began to interfere in the relations between masters and men. He then describes the circumstances which led to the appointment of successive Royal Commissions, charged to inquire into various matters relating to mines and miners, and he sketches briefly the leading features of the reports presented by these Commissions, together with the chief points of interest contained in the legislative enactments which were founded upon some of them. Our author also pauses from time to time to recount in considerable detail the events of more than passing interest, such as explosions, inundations, and other accidents which happened during the period with which he is dealing; and lastly, in his appendices, he gives the titles of the Acts of Parliament affecting coal mines and miners, both English and Scotch, a list of serious colliery explosions previous to and since 1850, and a table showing the production of coal at different times, commencing in 1660, and brought down to 1891.

Among other more or less important provisions of the Acts of Parliament our author gives prominence to :The exclusion of women from mines, the appointment of Government inspectors, the limitations of the ages at which boys can be employed, the restrictions under which explosives may be used, the requirement that each mine should have two distinct shafts, that each mine manager must have a certificate similar to that of a sea captain, that payment must be made by weight and not by measure, the conditions under which safety lamps are to be used, and the method of dealing with coal-dust when it is present.

He also reviews such questions as the payment of royalties and wayleaves to landlords, the employers' liability, the wasteful consumption of fuel, the duration of the coal supplies, and old-age pensions to miners.

Contrasting the present with the past he says:-"The workmen of the present day have attained a distinct social position, have representation in the House of Commons, and trade unions, societies, and powerful combinations," whereas formerly the Scotch colliers were adscriptæ glebæ, that is, were bought and sold with the

land: an Act of the Scotch Parliament of 1660 prohibited them from leaving their employment without a written attestation from their masters under pain of punishment in their bodies, and any person employing them was ordered to return them within twenty-four hours or pay a fine of one hundred pounds Scots. The colliers of the North of England were little better, being hired by the year under a system of binding or bonding; those of the Bristol coal-field were described by contemporary writers as being as brutal and ignorant as savages. Colliers lived apart from the rest of the community, were looked down upon with contempt by their fellow-men, and diverted themselves with bull-baiting, drinking, and debauchery.

The state of serfdom was removed by various Acts of Parliament passed during the latter half of last century, apparently more with the object of increasing the numbers of the colliers by drawing other classes of labourers into the mines than from any specially humanitarian motives. But at length a day dawned when higher principles began to prevail. From 1842, when Lord Ashley's Act was passed for the exclusion of women from the mines, onwards to 1887, one Act was passed after another, each having the same object in view, namely, the amelioration of the lot of the miner.

The frequent occurrence of disastrous colliery explosions and the great destruction of life and property which accompanied them, had done more than anything else to draw the attention of the public to a consideration of mining affairs, and had likewise been the principal incentive to the appointment of Royal Commissions and to the passing of Acts of Parliament to regulate the supervision and the working of mines.

Notwithstanding all that had been done previously, more lives were lost in explosions during the five years ending 1870 than during any preceding five years, the aggregate number lost in fifteen explosions, each of which involved the loss of ten lives and upwards, having amounted to 923.

The Coal Mines' Regulation Act of 1872 was drawn up with great care by Mr. Bruce (now Lord Aberdare), the Home Secretary. It embraced the experience of the Inspectors of Mines, as well as the combined wisdom of mine owners, engineers, managers of mines, and delegates of the colliers. But, firedamp having been hitherto regarded as the sole cause of colliery explosions, the stringent provisions of that Act were directed exclusively towards the detection and removal of that element of danger.

In 1845 Messrs. Lyell and Faraday, who had examined the scene of the Haswell colliery explosion, which they attributed to large accumulations of firedamp in the empty spaces (goaves) from which pillars had been removed, remarked that firedamp had not been its only fuel, but that doubtless the coal-dust which was raised and swept along by the firedamp flame would be decomposed by the heat of that flame, and would therefore add to the force of the explosion.

Between the years 1860 and 1875 several French mining engineers were impressed with the idea that coaldust had played a part in certain explosions which took place in France. Some experiments were made by a committee of the Société de l'Industrie Minérale, and by M.

Vital, one of the Ingénieurs des Mines, with the object of ascertaining the likelihood or otherwise of this hypothesis, but no definite conclusions were arrived at.

air such as had been used in our own apparatus, of which it was otherwise a copy.

The German Commissioners erected and made experiments with an apparatus similar to one that we had described to the Royal Society in 1881, but on a somewhat larger scale, and they obtained similar results. Unfortunately, however, they passed away from the main question, viz. whether an explosion that has fakes place in a dry and dusty mine under the circumstances that would have been formerly described as mysterious, can be attributed to the influence of the coal-dust in the supposed absence of firedamp?

The French Commissioners arrived at conclusions adverse to the coal-dust theory. They made no special experiments with coal-dust on an important scale and they did not, so far as can be gathered from their reports, examine the workings of any mine immediately after an explosion.

In December, 1875, the present writer examined into all the circumstances attending a colliery explosion in South Wales, and gave a minute description of it before a coroner's jury. He insisted that coal-dust had been the principal agent in that explosion, and that firedamp had only played a subordinate part. At the same time he referred to the results of experiments he had made which showed conclusively that when fine dry coal-dust is added to a mixture of air and firedamp, in which the firedamp is present in so small a proportion as to escape detection by the means employed for this purpose in mines, the mixture is inflammable at ordinary pressure and temperature, and when ignited burns like a jet of inflammable gas. In March, 1876, he read a paper before the Royal Society, in which he described these experiments, as well as the apparatus with which they had been carried out. In this paper, also, he claimed that when an explosion which we had previously stated in this country, sion is once begun in a dry and dusty mine it becomes self-propagating, and, provided the continuity of the deposit of coal-dust is unbroken, it extends to the utmost limits of the workings. This became known afterwards as the "Coal-dust Theory of Great Colliery Explosions." In May, 1876, Mr. Hall, one of the Inspectors of Mines, read his first paper on the subject before a meeting of the North of England Institute of Mining and Mechanical Engineers held in London.

During the year 1878 the present writer published a

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series of papers on Coal-dust Explosions" "in "Iron";

and while they were appearing Messrs. Marrecco and Morrison read their first paper on the subject.

Numerous societies of mining men, and individuals more or less connected with mining, now began to take an interest in the subject, and to make experiments with coal-dust. About this time, also, Commissions were appointed by the Governments of England (Royal Commission on Accidents in Mines 1879), France (Commission du Grisou), Prussia and Austria, to inquire into the causes of mining accidents, and amongst other things to investigate the probable influence of coal-dust in colliery explosions.

This sudden activity was no doubt quickened by the events of the ten years ending with 1880, during which the loss of life from explosions was twice as great as it had been during any previous decade. Taking into account only those explosions in which ten lives and upwards were lost, we find that there were thirty-five explosions, involving the lives of 2014 persons, of which 1411 were attributable to the second half of the decade. In 1880 Prof. (now Sir Frederick) Abel, one of the English Commissioners, was instructed by the Home Secretary to investigate and make a special report upon the Seaham colliery explosion (September 8, 1880). During the course of these investigations Abel repeated our experiments of 1875-76 with a similar apparatus with practically the same results as far as col-dust is concerned; but he claimed in addition to have dis covered that any very finely divided incombustible dust would render a mixture of air with 3 or 4 per cent. of firedamp inflammable. His apparatus was not, however, provided with any special means of mixing the gas and

The Austrian Commissioners arrived at the conclu

namely, that the relative fineness of a dust has far more to do with its relative inflammability than its chemical composition.

The English Commissioners expressed an oracular opinion. They denied on the one hand that coal-dust could be the principal agent in great colliery explosions, for, "If that were the case," said they, "an explosion would happen every day, nay every hour." But, on the other hand, they endeavoured to point out that coal-dust may be an element of the gravest danger under certain circumstances which they proceeded to define in a very precise manner. The Act of 1887 embodies their recommendations regarding safety lamps, explosives, and coal-dust.

From the end of 1875 onwards attention had been more and more directed to the coal-dust question. I: had been observed that a great explosion never by any chance took place in a damp or wet mine, that when such an explosion took place in a dry and dusty mine, its progress was always arrested by dampness or wetness or by the absence of coal-dust, that it always passed through the dry intake airways, which contain pure air, and comparatively clean coal-dust, that it frequently avoided the return airways, which contain all the firedamp produced in the workings, but impure coal-dust or only stone-dust, and, lastly, that it spread into all the districts of the workings ventilated by separate and distinct intake and return airways, quite irrespective of the force or direction of the ventilating currents, and dependent onl upon the one simple but indispensable condition that the train of dry coal-dust continued unbroken, or was interrupted only for short distances here and there. The facts were proved to demonstration by the researches of a number of independent observers in the mines themselves. immediately after the occurrence of explosions. Invas have the opponents of the coal-dust theory, who were 31 one time very numerous, urged that the intake airways might have contained firedamp, that the coal-dust clo raised and ignited by a local disturbance, such as the firing of a blasting shot, probably acted as a connecting link which carried the flame from one accumulation firedamp to another, that if coal-dust was as dangero as it was represented to be, an explosion would take pla

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