gienic conditions are favourable to disease, and on the contrary that a strict adherence to the ordinary principles of health will greatly modify if not prevent attacks of disease. Plenty of pure air and water, cleanliness, a sufficient supply of good food, and efficient removal of all excreta are fundamental points admitted by all; but something more than these are necessary as regards especially epidemic diseases, viz., the exclusion of the morbific poison which is the materies morbi of these diseases.

The means of disinfection used are intended (1) to destroy if possible the morbific poison utterly; (2) to suspend its action and arrest its propagation if destruction cannot be conveniently accomplished.' The first is to be effected by 'exposure to free currents of air, by using certain chemical agents, or by heat.' 'The second may be accomplished by great cold, or by certain chemical substances.' The exposure to free currents of air is uncertain and slow, whilst the vapours of certain agents, as of chlorine, nitrous acid, and sulphurous acid, are more speedy and efficacious. Other disinfectants, such as chloride of zinc, permanganates, and salts of iron, must come in contact with the matter to be destroyed. To this latter statement of Dr. De Chaumont many will object; for instance, the advocates of the use of the permanganates do not agree with the doctrine that it cannot be used by dif fusion in the air in the same way as chlorides, and therefore strongly advise that cloths dipped in the solution be stretched on lines across the sick chamber, or an open doorway. Heat is considered the best disinfectant, and we believe this will be admitted by all, provided it be used dry at a temperature of from 230° to 250° Fahr., or in the form of of superheated steam. The temperature of boiling water, which is stated by Dr. de Chaumont to be sufficient in most cases, is not considered to be high enough by some of our best chemists and experimenters.

The next method of disinfection by the use of carbolic acid, chloralum, and other substances which do not destroy the poison, is still very efficacious, as they arrest its activity for a longer or shorter period, according to the strength of the solution used. There is, however, one view of the action of carbolic acid which has been overlooked by our author, viz. that if the infected articles be disinfected by carbolic acid, they can be removed from the immediate neighbourhood by water-carriage or otherwise to a distance, and so diluted by the air or water as to become innocuous, and eventually destroyed.

Isolation is a most important precaution in preventing typhus, small-pox, and scarlet fever, but appears less effectual in regard to measles perhaps because its particular poison may be carried more easily through the air.' The isolation should be complete both as regards the patient and his clothes and bedding. As to quarantine, Dr. de Chaumont believes that if it could be rigidly carried out it would step epidemics from without, but the whole question is so surrounded with difficulty, and so partially carried out, that it is often a positive nuisance, and absolutely useless, and in this we agree with him.

As regards the Contagious Diseases' Act he is satisfied that very strong testimony in its favour has been afforded by the operation of similar Acts in Malta, Calcutta, and many places abroad. That it is important to carry out the Act in garrison towns because of the sickness of the soldiers, which he believes would be reduced one half if syphilitic diseases could be prevented. He considers all the objections to have but little force compared with the benefits which would be derived from it being efficiently put in practice.

The laws of propagation of disease and epidemics afford a wide field for discussion, but in which we have at present made but little progress, as, although some fallacies have been got rid of, we still have some advocating the view of a general morbific poison, whose special varieties produce particular maladies; others, who deny any special poison at all; some insist upon it that each disease has its own special germ; whilst others are sure that the germs may arise de novo. Some credit a fungus with the bad pre

eminence, and some adopt the bacterium as the fons et orizo mali.' Dr. de Chaumont remarks that space would not allow of his discussing all these, but believes that the majority are in favour of a special poison producing a particular disease, and considers the objection that hybrids are occasionally formed, as Rötheln or measly scarlet fever, to be in favour of the special poison theory. The doctrine of evolution may, perhaps, be applied to these diseases, as it alleges only the gradual development of the type into another until a high state of perfection is attained, when the chances of further development are greatly lessened. On the other hand, when the limit is reached the type tends to decay; at the same time this limit may be shifted in the course of ages, and fresh integrations starting from other points may reach a higher stage. The same theory may apply to other diseases, and account for the disappearance of some which no longer occur. On the other hand, what value can we attach to the theories of the spontaneous origin of disease, by which germs are supposed to arise either out of previously existing organic matter, or else from certain combinations of inorganic matter. There is no evidence of real value as to the first view; and as regards the second, we think that the supporters of it have not understood the tremendous nature of the postulate they demand.' The force required would be enormous. Thus a gramme of hydrogen in burning evolves heat equivalent to 47'5 foot-tons, and of carbon equal to II foottons. Conceive the force which must be required for the integration of the most minute particle of organic matter, and the much greater force for the most minute organism capable of independent existence.

He goes on to say that Chauveau, Sanderson, and others have shown by experiment very good cause for believing that there is a special poison in such diseases as small-pox, and that that poison is particulate. It seems, however, strange at first sight, that such diseases should be more rife at one time than another, unless there be some occult influence as the determining cause. Dr. de Chaumont thinks that it is unnecessary to assume the existence of such causes, as it seems to him that after an epidemic the number of persons susceptible to an attack has been so much diminished as to account for the cessation of the epidemic, and that an invasion of the disease will not again occur until the number of 'epinosic individuals' has again considerably increased. It seems to us, however, if the invasion of an epidemic depends only on the number of epinosic individuals (i. e. of those susceptible of an attack), that the recurrence of an epidemic in such diseases as measles and scarlet fever, which attack chiefly children, would be determined only by the birth-rate, and would therefore vary but little in the length of their epidemic waves. Now the statistical calculations of Dr. Tripe on scarlatina, referred to by Dr. de Chaumont (see SANITARY RECORD, May 8, 1875), show that whilst the average annual mortality in each epidemic since 1853 has not varied twenty deaths per 1,000,000 population, yet the length of the epidemic waves has been gradually increasing, having been of three years' duration in 1853-55, then of four, next of five, then of six years for the epidemic of 1865-70; whilst that of the present epidemic will almost certainly extend to the end of 1877, and perhaps of 1878, being a period of seven or eight years. If the number of epinosic individuals in London alone determines the death-rate, why does the intensity of the epidemic influences vary so much as to have caused a much smaller number of deaths than the average for the last five years? Statistics are at the bottom of all inquiries of this kind, and it is therefore of great importance, not only that no false facts be registered, but that no hasty or erroneous inferences be drawn from them. We should not only remember that a small number of observations is inadequate to establish a fact, but also that a mere repetition of observations beyond a certain point is proportionably of small additional value. Calculations are given which fully support this proposition. But he observes that the more statistics are extended embracing fresh facts and

analysing old ones, the more valuable will they be.' Dr. de Chaumont then proceeds to discuss the recent attacks on the Registrar-General's death rate as values of the sanitary state of different districts, and thinks that the objectors have been hypercritical, as 'accidental causes acting through a length of time tend to neutralise each other.' Here again he seems to have looked at the objections only which referred to all England, and to have overlooked those for the metropolis, which belong to a different category altogether, as they are not based on accidental causes. We agree so entirely with Quetelet's four chief rules, which Dr. de Chaumont says should be hung up in every room or office where figures are dealt with, that we copy them for the benefit of our medical and sanitary statisticians:

1. Never have preconceived opinions as to what the figures are to prove.

2. Never reject a number that seems contrary to what you might expect, merely because it departs a good deal from the apparent average.

3. Be careful to weigh and record all the possible causes of an event, and do not attribute to one what is really the result of the combination of several.

4. Never compare data which have nothing in com

mon.

Dr. de Chaumont concludes as follows: 'We try to prevent disease as well as death, and if we can do this, and so induce hereditary immunity, there is no reason why our weakly ones of to-day may not be the parents of a strong and intellectual race in the future. Under any circumstances our duty is clear, to improve the condition of our race according to our lights, and let the results take care of themselves. The same law of development will, sooner or later, teach us if we have taken the right road or not, to reach the wished-for goal.'

The length to which this review has extended shows the value we place on this work, and we trust that we have given such an analysis as will enable our readers to judge for themselves how far it is likely to meet their wants. We need scarcely say that we consider it an important addition to the other works published on this subject, and can strongly recommend it to those who require information of the most recent date.

Correspondence.

THE GENESIS OF TYPHOID FEVER.

(To the Editor of the SANITARY RECORD.) SIR,-In answer to the letter from Dr. Mackintosh in your last issue, I will, with your permission, make the following remarks.

Nothing that I wrote implied that typhoid fever only comes from the evacuations of typhoid patients, nor that it 'can only exist where it has existed before, or where it has been conveyed by persons or things.' That is to say, I did not allude specially either to the specific or to the nonspecific theory of the origin of the disease. The distinction I did wish to draw was between organic matter of animal, more especially of excremental origin, and that of vegetable origin, as being the cause of typhoid fever.

I should not have been surprised if protracted cases of diarrhoea had been caused by, and had been attributed to, the use of water contaminated with vegetable organic matter, because there can be no doubt that this, amongst numerous other causes, is capable of producing that disease. But before I could be convinced that a few rotten turnips in drinking-water can produce a disease like typhoid fever, which is characterised by well marked and definite lesions, I should want much more exhaustive evidence than Dr. Mackintosh has offered in his letter, and I should want all other possible causes of the disease eliminated. But he is silent on this point.

Were the characteristic lesions belonging to the disease

looked for and found by post mortem examination in the cases which proved fatal? I think that positive evidence of this sort is necessary if we are asked to come to the conclusion that typhoid fever was due to what appears to me, and what I believe will appear to the majority of your readers, to be an unusual cause.

Dr. Mackintosh does not give any analysis of the wellwater in question, so that we are in the dark as to whether or not there was any excremental pollution of the water. Owing to the wretched sanitary arrangements which prevail in most rural districts, pollution of this sort is so common in shallow well water, and not less so in that from the mill-stone grit than in that from many other geological formations, that in the absence of positive proof to the contrary, I should strongly suspect its presence in addition to` the contamination with vegetable organic matter.

6

Again, Dr. Mackintosh does not mention whether there were any other insanitary conditions common to the cottages where the disease occurred, such as any accumulations of filth, bad drainage, or ill constructed privies. If any such existed, might it not have been possible for the water to have become polluted with excremental matter? Any of this that might have gained access to the well would have been removed, as well as the turnips, when the well was cleaned out, water and all.' And inasmuch as he observes that 'isolation and disinfection, with other precautions, were recommended and adopted during the outbreak in every infected house,' I presume that the removal of any such insanitary conditions as I have indicated would be included in the other precautions.' Moreover he has not mentioned how many susceptible persons were drinking the well water at the end of the outbreak. Therefore the information contained in his letter does not convince me that the outbreak was caused by the presence of the turnips in the water, nor that its cessation was due to their removal from the well; and unless he can prove that there was no possible source of excremental pollution of the air, and more especially of the water, he will certainly fail to convince me that typhoid fever can be produced by drinking rotten turnip water. ALFRED ASHBY, Medical Officer of Health, Grantham, Newark, and Sleaford Combined Sanitary District.

Grantham, Feb. 2.

APPOINTMENTS

OF HEALTH OFFICERS, INSPECTORS OF NUISANCES, ETC.

BURNLEY, Henry, Esq., has been appointed Chairman of the Normanton Urban Sanitary Authority, vice Walker, resigned. EASTWOOD, Mr. T. W., has been appointed Clerk to the New Todmorden Urban Sanitary Authority.

FIELDEN, Mr. William, has been appointed Collector to the New Todmorden Urban Sanitary Authority.

FOWLES, Mr. Frederick, has been appointed Inspector of Nuisances for the Hereford Rural Sanitary District, vice Davies, deceased. HODDING, Mr. F., has been appointed Clerk to the Alderbury Rural Sanitary Authority, vice Jesse, deceased.

HOWELL, Mr. E. W., has been appointed Inspector of Nuisances for the Stoke-on-Trent Urban Sanitary District, vice Steele, whose appointment has expired.

JONES, Thomas Henry, Esq. (of the North and South Wales Bank), has been appointed Treasurer to the Wrexham Corporation and Urban Sanitary Authority, vice Wyatt, deceased. MACKINTOSH, Angus, Esq., M.D., Lt. P.S.G., and L.M., has been unanimously re-appointed Medical Officer of Health for the Rural District of the Chesterfield Union, and the Urban Sanitary Districts of Whittington, Dronfield, Newbold c. Dunstan, Brampton and Walton, and Clay Lane, in the county of Derby. PAULL, Mr. H., has been appointed Clerk to the Chard Rural Sanitary Authority, vice Gould, resigned.

ROCH, Nicholas Adamson, Esq., has been appointed Chairman of the new Milford Port Sanitary Authority.

RODLEY, Mr. F., has been appointed Surveyor to the New Todmorden Urban Sanitary Authority.

TERILL, Mr. W. F., has been re-appointed Inspector of Nuisances for the Alderbury Rural Sanitary Districts.

WRIGHT, Mr. N. W., has been appointed Clerk to the North Bierley
Rural Sanitary Authority, vice Lancaster, resigned.
YOUNG, Mr. Jonathan, has been appointed Inspector of Nuisances
for the Parish of Chelsea, vice Mr. Hugh, resigned.

VACANCIES.

BEDFORD RURAL SANITARY DISTRICT. Inspector of Nuisances : 2001. per annum. Application, 22nd instant, to Mark Sharman, Clerk to the Authority. GLAMORGANSHIRE. Public Analyst: 27. 12s. 6d. for each statutory report, 15s. for each analysis and certificate, and 10s. 6d. for attending as a witness at the place where he resides, or 21s. with 35. per mile going out and returning elsewhere. Application, March 1, to T. Dalton, Clerk of the Peace, Cardiff. KINGSTON-UPON-HULL. Town Clerk, Clerk to the Urban Sanitary Authority, Registrar of the Court of Record, and Steward of the Manor of Myton: 1,000l. per annum, and 27. 25. per day and railway fare when absent on Corporation business. Application, 5th instant, to George C. Roberts, Town Clerk. LEICESTERSHIRE.

Public Analyst: tos. 6d. per analysis: minimum, 60l. for one year. Application, 7th instant, to W. Napier Reeve, Clerk of the Peace, Leicester.

SOUTHMOLTON RURAL SANITARY AUTHORITY. Treasurer.

ST. IVES, Cornwall. Treasurer to the Corporation and Urban Sanitary Authority.

STRATHAVEN, Lancashire. Certifying Factory Surgeon. STRATTON RURAL SANITARY DISTRICT, Cornwall. Medical Officer of Health, South District. Application, 7th inst., to W. Pickard, Clerk to the Authority. SWADLINCOTE URBAN SANITARY DISTRICT. Medical Officer of Health Surveyor, Inspector of Nuisances, Collector, and Market Hall Keeper: 100l. per annum. Applications, 5th instant, to W. P. Dewes, Clerk to the Authority, Ashby-de-la-Zouch. SWANAGE URBAN SANITARY DISTRICT. Surveyor and Inspector: 70l. per annum. Application, 12th instant, to James Roe, Clerk to the Authority.

TRURO URBAN SANITARY DISTRICT. Medical Officer of Health: 40%. for one year. Application, 5th instant, to J. H. Cock, Town Clerk.

WEYMOUTH RURAL SANITARY AUTHORITY. Clerk.

NOTES, QUERIES, AND REPLIES. All communications must bear the signature of the writer, not necessarily for publication.

ENCOURAGEMENT FOR SMOKERS.

THE Bath Chronicle announces the death in that city of Abigail Warton Morrison, in her rooth year, and the Dorset Chronicle says an inmate of the workhouse named Joha Chaffey has just died at the age of 104 years, and adds--' Chaffey was a great smoker.'

THE PARISIAN MEDICAL NIGHT SERVICE. THE new plan adopted in Paris, by which persons requiring night medical assistance can send to the police stations, a policeman accompanying their messenger to the surgeon's house, is said to be working well. In one arrondissement more than eighty applications have been made since the year began, and not one of the doctors who have entered their names on the police list refused to attend.

DRUNKENNESS.

SPEAKING at the annual meeting of the Discharged Prisoners' Aid Society, the Earl of Lichfield affirmed that it was fallacious to say drunkenness was the root of all evil, for, while in Staffordshire it had increased 300 per cent, during the year, serious crimes had diminished 30 per cent. The Bishop of Lichfield disputed this reasoning, and said that drunkenness was eating up the vitality of religion and the life and industry of the nation. It could no longer be winked at, and Parliament must interfere to preserve the country.

cent

THE SANITARY CONDITION OF BERLIN. AN interesting paper on the sanitary arrangements of Berlin and other large German towns has been read by Dr. Stamm to the members of the Berlin Hygienical Society. He showed that from 1867 to 1873 the average mortality in Germany was one in thirty-three, while for the whole of Europe the average was one in forty-two only; that the mortality of Berlin is considerably greater than that of Paris, Amsterdam, or London; and that it has been from three to eight per more than in the country districts in its immediate vicinity. Dr. Stamm attributes this mainly to the overcrowding of the popula tion in the poorer quarters of the capital, owing to the exorbitant rates to which house rent has risen during the last few years. The number of people residing on each hectare of ground in Berlin is nearly five times as great as in London. The practice of letting houses for a long period at a fixed rent, as in London and Paris, is almost unknown at Berlin, where the landlord, owing to the scarcity of accommodation, is nearly always sure of a tenant, even at an increased rent. Numbers of people live in cellars; houses may be built as high as the street is wide, and a small courtyard at the back is often made a pretext for adding three or four more storeys. In 1867 there were 15,574 dwellings in Berlin where upwards of six persons lived in one room, and 14,292 cellar-dwellings, and since then the evil has considerably increased. Dr. Stamm concluded by urging the Government to amend the legislation regarding house property in the German towns so as to make it unlawful to build houses of such a height as to be prejudicial to the public health, and to abolish altogether the practice of living in cellars.

LEAD PIPES.

THE following remarks on lead pipes in relation to buildings are extracted from an article on Lead in Relation to Architecture' published in the Builder of January 29. "The most ancient, that is to say, the Roman, method of making lead pipes was to turn a sheet of the metal cast to the requisite thickness on a stout timber or iron mandril; and then to fuse or "burn" the edges together by means of a stream of red-hot lead,-poured on the joint through a level channel of clay,-which melted and thus combined the separate edges. This process-cumbersome, indeed, and sometimes ineffectual had long given place to a soldered joint, until in our day it has been resuscitated, as it were, by the use of the oxyhydrogen blow-pipe. But we need hardly tell our readers that both of these old-fashioned methods have been superseded first by the ordinary drawbench; and, secondly, by the hydraulic press-the last of which is an uncommonly beautiful process, and renders the use of solder altogether unnecessary. This mechanical innovation-however it may affect the business of the artisan skilled in the use of the copper bolt--is not altogether a matter for regret. For the objection we made to solder in any form upon roofs applies with still greater force to solder especially in soil-pipes. There is, in that case, a physical action, properly so called; a chemical action and an electrical action. Solder, which is an alloy of lead and tin, is, singular enough, more fusible than either, but then it is harder than both. Again, tin is a very much better conductor of electricity than lead; hence a case of action and re-action, which we need not stay to explain. Once more the solid, liquid, and gaseous matters which separately or in combination go to compose the sewage of our domestic soil-pipes tell differently on the separate metals; and in point of fact we find that soil-pipes invariably give way at the soldered joints. Besides, it must be told that soldering is frequently executed in such a slovenly fashion as to render the interior surface of the joint a sort of serrated ridge of projecting spikes, to the great obstruction of the thoroughfare. For this reason alone the cast-lead syphon trap is preferable to a soldered one. Supply-pipes are of course never soldered excepting at the points of junction in the lengths, and this, the well-known form of plumber's joint, is, when carefully performed, one of the most useful and scientific operations in the whole range of the mechanical arts.

The use of lead in water-cisterns, although in many respects a very convenient application of the metal, is not by any means without danger in a sanitary point of view, and is, therefore, more or less objectionable. Of course, no other material, even slate or cast-iron, can be made so absolutely water tight. The lead for a cistern is usually cut in three pieces from the sheet-the bottom and two sides in one the two ends separately, soldered together at the vertical corners by the technical process termed "wiping," which is effected by a cloth saturated with grease and a redhot iron. Those who have tried to do this little job, and burnt their fingers at it, as we have done in our hot youth, will better understand than we can describe it. The waste pipes, water-closet valves, hot-water pipes, and so forth, are all attached to the cistern in the same manner; and yet, as we have said, although probably the safest in one respect, it is not the best means of storing water for domestic use, and we will try to explain in a few sentences the reason. Lead pipes, lead cisterns, lead vessels--in short, lead in any form, used in connection with water-supply, contains a possible and a very potent element of poison !

Lead is a metal which, as we have pointed out, is peculiarly prone to oxidation; and therefore a study of the combined action of air and water on lead is of great importance, in consequence of the metal being so frequently employed in the construction of cisterns and water-pipes. The true chemical reaction is simply this-the lead becomes oxidised at the surface, and the water dissolves the oxide; this solution absorbs the carbonic acid of the atmosphere, a film of hydrated oxycarbonate of lead is deposited in silky scales, and a fresh portion of oxide of lead is formed and dissolved, and in this way a rapid corrosion of the metal ensues. This action is materially increased by the presence of some salts, and diminished by the presence of other salts in the water. It is much increased, for example, by the occurrence of chlorides (which, as chloride of sodium is often present in spring water), and of nitrates and nitrites (which are often present in spring and river waters, from the decomposition of organic matter); while it is diminished, on the other hand, by the sulphates, phosphates, and carbonates, and especially by carbonate of lime, which is an extremely common impurity in spring water. In the latter case, a film of insoluble carbonate of lead is rapidly formed on the surface, and the metal beneath is thus protected from the action of the water. If, however, the water contain much carbonic acid, the carbonate of lead may be dissolved in its turn; and on the whole, considering the dangers which constantly arise from the use of water impregnated with lead, cisterns constructed with slate, or even of cast iron, are far preferable to leaden ones. This poisonous tendency of the metal is accordingly one of the great problems of water supply, since the purity of the water is the greatest factor of the oxidation, and consequently of the solution, of the metal. It is impossible to interpose, as has been often suggested, any obstacle to this chemical action, such as plates of zinc or layers of sand or lime, for the obvious reason that these preventives need more attention than a hot-air furnace or a gasmeter. Lead pipes, or even composition pipes, the basis of which is lead, are decidedly inferior to tin or iron, or even lead which is lined with tin.'

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of Hackney commenced an action in Chancery against Mr. de Morgan.

The three actions referred to came up before the Court of Chancery on January 27. The first action was Austen ข. Amhurst-an action brought on behalf of certain Hackney commoners claiming rights of common over the Hackney Downs. The second action Amhurst v. de Morgan was that in which the lord of the manor, Mr. Tyssen Amhurst, moved for an injunction to restrain the pulling down of his fences, and the third action was the one previously pending between the Attorney-General at the relation of the Metropolitan Board of Works, and the lord of the manor of Hackney, by which it was sought to restrain the lord of the manor of Hackney from exercising his alleged rights of erecting fences and digging gravel on and from the Hackney Downs, as things inconsistent with the alleged rights of the public under the scheme of the Metropolitan Board of Works for the regulation of the Hackney Downs. This action is the one previously alluded to as having been instituted in the first instance by the Metropolitan Board of Works against the lord of the manor of Hackney. On behalf of the Commoners referred to above, Mr. A. G. Martin, Q.C., and Mr. Woodroffe moved for an injunction to restrain the lord of the manor until the trial of the actions from erecting fences and digging gravel. Mr. Elton, who appeared on behalf of the lord of the manor, stated that the digging of gravel had ceased on the Hackney Downs, and he was willing to undertake to dig no more gravel pending the trial of the actions. Mr. de Morgan having at an open air meeting declared his intention of inducing the pulling down of fences which the lord of the manor had erected on the North Mill Field, another of the Hackney Commons, it was demanded on behalf of the lord of the manor that an undertaking should be given on the part of Mr. de Morgan not to pull down or interfere with the existing fences on the North Mill Field or to incite any other person to pull down these fences pending the trial of the actions, with liberty to apply to advance the hearing on an undertaking by the lord of the manor of Hackney not to dig gravel or make enclosures in the meantime, and an undertaking on the part of Mr. de Morgan not to interfere with any existing fences, or to incite any other persons to interfere with them.

different issues. The first action was commenced by the Metropolitan Board as a board representing the ratepayers of the metropolis, and in its own name; and it was taken presumably under the authority of an Act of Parliament specially relating to the preservation of metropolitan commons. The second action is taken in the name and on behalf of persons claiming rights of common over what are called the Hackney common lands. For the issue of contention the public will naturally look with unusual interest. Meanwhile, it is probable that the Conference recently held between a Sub-Committee of the Metropolitan Board of Works and a Sub-Committee of "The Hackney Commons Local Defence Committee' will lead to the speedy commencement of another Chancery suit in reference to the Hackney Commons.

EXPLOSIONS

COLLIERY
PREVENT-
ABLE BY POSITIVE VENTILATION.
BY ALDERMAN TAYLOR, ROCHDALE.
Read before the Society for the Promotion of Scientific
Industry, Manchester.

THREE years ago a fellow-townsman of mine, Mr. Andrew Pilling, took out a patent for ventilating mines. Some months ago he drew my attention to his invention, and I believe after thorough investigation that the practical application of his invention will be of great value. I am glad of the opportunity afforded to me this evening by the Society for Promoting Scientific Industry to bring before it and the friends kindly invited the question for the first time publicly, and I hope I shall be able to show that we have reduced the plan to such simplicity that there can be no objection raised to it. The method of ventilating coal mines advocated in this paper I have termed 'positive,' because it is different from all other known methods, namely, the furnace, the fan, and the steam jet, or the pump, which are negative. The positive method consists in forcing the air into the mine by the piston, and regulating its pressure and velocity at the exit. By the adoption of this plan the ventilation will be under complete control both as to quantity and certainty, and moreover will be perfectly independent of atmospheric changes. The defects of the present modes of ventilation are that they are influenced by every barometric change; that by the absence of all pressure, except atmospheric, the ventilation is uncertain and variable in the different parts of the mine, and there is no scientific control. The whole of these defects are remediable by the plan we are about to consider. That the subject may be fully grasped we will draw the attention to statements made concerning venti

The subject may at this point be dismissed with the following observation, namely, that two of the actions already referred to, that is to say, the one originally commenced by the Metropolitan Board of Works and the new action commenced at the instance of certain Commoners of Hackney, attempt to raise

ceived as somewhat authoritative. The extracts we shall give are first from two of the Hermon Prize Essays on the 'Prevention of Explosions and Accidents in Coal Mines,' written by Mr. Wilfred Creswick and Mr. W. Galloway. Mr. Creswick observes 'If the roof and floor of all mines were perfectly smooth and regular. . . . but no such roof and floor are ever to be found, and the liability of either to break renders the ventilation of coal workings, especially deep ones, so subject to outbursts of gas from roof and floor as to make me despair of ever getting sufficient atmospheric air through the galleries of mines to mix with and dilute the fired amp given off in these outbursts, not even if the air travelled at a fabulous rate, for the liberated gas and