tained throughout the whole of the interior of the inner box, and a uniform and penetrating, but moist heat is constantly generated.

The outlet from the inner box is provided with a valve which can be regulated at pleasure.

The lid by which the box is closed at the top is shown at E, and this can be worked either by balance-weights, or by rachet-wheels, which are easier to actuate.

The box can also be made with the front or the ends to open.

To conclude this short description of the apparatus, we may point out that the means of upholding the articles placed in the interior of the box are by rods placed across the inner box at F. A similar grating is placed just above the bottom of the inner box at H to receive other materials requiring disinfection. As a matter of course, so long as the principle is preserved, so that no moisture or condensation be gathered from the atmosphere, and an uniform penetrating heat insured in the interior, the apparatus can be constructed of such a size as readily to take in whole mattresses, chairs, or sofas; the only difference being that mattresses would take longer to disinfect on account of their thickness. For furs, and such like articles, an uniform heat can be held in suspension by a very little proper regulation.

The value of this new disinfecting apparatus, which justly obtained both a silver and bronze medal at the late International Health Exhibition, 1884, was sufficiently made manifest at a lengthy and crucial series of experiments conducted by Dr. Bartlett and other gentlemen some months ago. In little more than half an hour the temperature rose to 262° Fahr., and afterwards, for the space of 41 minutes, this suitable and nearly unvarying temperature was maintained at a total expenditure of 100 feet of gas. matters tested were cambric, muslin, calico, flannel, a flock cushion, bakers' yeast, and certain germinal matters. These latter were obtained from the air of an hospital, and included pus cells, bacteria, nomads, entozoa, and fungi.

The

The yeast

The result proved that, even at the high heat maintained, such was the uniform disposition of the heat and the removal of vapour that the fabrics placed even near the bottom of the box, were taken out perfectly uninjured and without loss of colour or textile strength. was completely sterilised, and produced no fermenting action upon sugar solutions, &c., and the germinal and fungoid growths were all killed, and could not be revived either by moisture or by treatment with Pasteur's solution. The mites, the vibrios from decomposed meat, and the human parasites were also destroyed. Other experiments have shown that linen, flannel, &c., have been subjected to 320° Fahr., and muslin to 300°, without sustaining the slightest damage. Bedding and mattresses are not only purified, but improved, inasmuch as the heat causes the filling-in material to expand, and thus saves the trouble of remaking them. It can easily be understood also that a second lot of materials can be purified in a less time with a diminished consumption of gas. Moreover, the apparatus, which can be made to run on wheels, is well adapted, not only for disinfecting purposes, but for drying and airing.

An apparatus, 7 feet 4 inches long, 3 feet 4 inches wide, and 3 feet 4 inches deep, outside measurement, has produced 280° of heat in 25 minutes, with a consumption of 70 feet of gas. Three hundred and fifty degrees can be obtained in 55 minutes, at an expense of 150 feet of gas, but this is more than what is necessary to destroy harmful agents. Practically, thorough disinfection of fabrics and utter destruction of hurtful germs and vermin can be achieved in this apparatus in one hour at a temperature of from 240° to 260° Fahr., with an expenditure of a little over 100 cubic feet of gas, which at ordinary rates would cost less than 4d.

Its simplicity, cheapness of working, and rapid action should recommend this disinfecting apparatus tɔ the authorities of hospitals, infirmaries, sanatoriums, schools, public institutions, and mansions, as being alike suitable for disinfection, perfect drying, and airing of all kinds of material. |

THE SILENT' SYSTEM OF VENTILATION FOR PRISONS.

THE ventilation of prisons has always been a matter of peculiar difficulty, as, owing to the necessity of having the cells thoroughly isolated from each other, any system that did not effect that object and at the same time secure a continuous change of air in each cell was practically useless. As there was really no system in existence whereby a number of cells could be ventilated into one shaft, and at the same time sound prevented from passing from one cell into another, Messrs. Robert Boyle & Son, the well-known ventilating engineers, have, after giving the matter the most careful consideration, devised an arrangement which is most ingenious and yet exceedingly simple, and there can be very little doubt but that it will effectually answer the purpose for which it is intended. The system may be described as follows:-Take a block or wing of a prison, consisting of, say, three tiers of cells on each side, composed of thirty cells on each tier or row, making 180 in all. Three brick flues, internal measurement 2 ft. x 2 ft, are built at equal distances against each of the side-walls, and carried up above the roof, where they are surmounted with the Self-acting Air-pump Ventilators, of 3 ft. diameter. Three horizontal shafts run along each tier immediately underneath the ceiling and close to the wall. Each of these shafts is connected with ten cells by means of protected openings, varying in size in proportion to the distance of the opening from the upcast shaft, so as to equalise the quantity of air extracted from each cell. Three of these horizontal shafts, one on each tier, are connected with one of the upcast shafts, which forms a junction in the centre. The horizontal shafts vary in size according to their proximity to the top of the upcast shaft, SO as to equalise the quantity of air drawn from each tier. A ring of gas jets is fixed at the bottom of the upcast shafts for the purpose of warming them in cold weather and preventing condensation of the ascending column of foul air. peculiar feature in this arrangement is that the ventilating opening in one cell is isolated from the openings in the other cells by means of a metal plate or partition extending from it along the shaft and past the opening of the second cell to it; and so on with all the other cells, they being treated in a similar manner, one partition plate overlapping the other the length of two cells from the one it is connected with until the central upcast shaft is reached, where a divisional plate is fixed in the horizontal shaft to prevent the two currents (travelling in opposite directions) from striking each other and creating a swirl as they enter the upcast shaft. Each partition plate is deafened round the opening into the cell by means of a double plate packed with sand. The horizontal shafts as they pass through the cells are also protected and deafened by means of a double casing, having the space between packed with sand.

The

The advantage of this system is that every cell is equally and separately ventilated, whilst perfect isolation is secured, it being impossible for sounds to pass from one cell into another through the ventilating shafts or openings, whilst as many as from ten to twenty cells can be ventilated by the one pipe, and three or four of these lead into one upcast shaft. An important feature is that there are no valves used in connection with any part of the system; so that when once fixed no further attention is required, and the ventilation cannot be interrupted through negligence, as is usually the case where ventilating alangements are employed that require looking after. Messrs. Boyle have entitled this arrangement the Silent' System of Ventilation for Prisons, a very appropriate

name.

Fresh warmed air is introduced into each cell through vertical channels cut in the walls protected outside and inside with strong iron gratings. These channels open into the galleries on the inside of the building, and are supplied with air from two large openings at each end of

CORRESPONDENCE.

Audi alteram partem.

[All communications must bear the signature of the writer, not necessarily for publication.]

AWARDS FOR VENTILATORS AT THE
LATE HEALTH EXHIBITION.

In reply to Mr. Clark's letter re the above, which appeared in your last issue, we have only to repeat that we were not invited to send our air-pump ventilator, which is the only exhaust ventilator we either manufacture or sell, for the purpose of being tested, nor were we notified that tests were being made with exhaust ventilators; we, as already stated, not being even aware that such tests were instituted until after they were completed and the awards made. Under these circumstances, it seems rather superfluous for Mr. Clark to say that we were not excluded from the testing, seeing that we-why, we cannot understand, though we mean to find out- were left in entire ignorance of the existence of such tests. Mr. Clark states that we were invited in proper form to send our ventilator to be tested, and also that he holds a letter from us declining to comply with his request. As this is really a matter of not only private but public interest, we now call upon Mr. Clark to publish the letter referred to, so that your readers may be enabled to judge between us, and that we may have the opportunity of showing how we have been treated.

With respect to our error in the length of the testing tube, stating that it was eight feet, whereas Mr. Clark informs us that it was ten feet long, this additional length, instead of improving the position, shows all the more conclusively that the mode of testing was a farce, and we are prepared to argue this point with Mr. Clark either as a question of science or practice, or as both, and to prove the correctness of our assertions, which we make as practical men of extended experience.

From the accounts we have since read of the experiments and the manner in which they were conducted, we much fear that they will have the effect of bringing sanitary science into discredit with the public, and do it almost as great an injury as the notorious Kew Experiments, which is greatly to be regretted, as it retards and hampers the efforts which earnest and practical men are now making to popularise the cause amongst the people.

We derived the information from a credible source that the shafts of the ventilators tested were inside the tube, but, as Mr. Clark affirms, and we have no knowledge of ourselves to the contrary, that such was not the case, we will concede the point, which does not affect materially

the method of testing the ventilators.

As we in the whole course of our experience as ventilating engineers have never heard mention of Mr. Clark as an authority on ventilation, it might, as indicating the value to be attached to that gentleman's labours, be satisfactory to your readers, as it certainly would be to us, to be informed of his qualifications to decide a question relating to ventilation in such an off-hand manner, which has hitherto baffled the most scientific and practical experts on the subject, viz., the determining by scientific experiment the relative values of ventilating cowls.

Mr. Clark stigmatises part of our letter as 'abusive.' If stating that we will not allow this matter to drop until we have sifted it to the bottom and discovered the individual or individuals really to blame is abuse,' then we

Queen Anne's Buildings,

64 Holborn Viaduct, London, E. C.,
Nov. 4, 1884.

To Sir Philip Cunliffe-Owen, Secretary to the late Health
Exhibition, South Kensington.

Dear Sir,-We are informed, and for the first time, that the exhaust ventilators exhibited at the late Health Exhibition, South Kensington, have been submitted by the jury to a series of tests, with the view of ascertaining which was the best and entitled to the first prize. As we received no notification that such tests were going to be made, nor were invited to submit our self-acting air-pump ventilator, exhibited at the Health Exhibition, for the purpose of being tested along with the others, we beg to ask you, as the representative of the jury, for an explana tion of the omission, and the reason for our ventilator being excluded.

We have also to ask you if it is correct that Mr. J. P. Seddon, architect, formed one of the jury on ventilation, and that five medals have been awarded to the ventilating and sanitary appliances of a firm which that gentleman has been the public advocate of for these last seven years, he being also well known to be strongly antagonistic to us personally and to our ventilating arrangements?

During the time of the Exhibition we repeatedly attempted to ascertain the names of the jury; but, for reasons best known to that body, none of their names were allowed to be divulged-an unprecedented proceeding, and entirely contrary to the recognised rules which control all Exhibition juries. We beg to remark, however, that in England men do not submit to be condemned by secret tribunals without even having been brought to trial, as is the case with us in the present instance.

Enclosing a pamphlet containing the notorious Seddon correspondence re the application of our system of ventilation to the London Custom House, and hoping to be favoured with an early reply to the foregoing queries, We have the honour to be, Your obedient servants,

(Signed)

ROBERT BOYLE & SON. given for ventilators, on the grounds that our self-acting P.S.-We beg formally to protest against the awards air-pump ventilator was not tested, and that we were not invited to submit it for the purpose of being tested along with the others, and that therefore the awards given do not show that the ventilators receiving them were justly entitled to them. R. B. & S.

As it is evident, from the position Mr. Clark has taken up, that the above letter has failed in its purpose, and

that we may expect but scant satisfaction at the hands of the gentlemen-whoever they may be-who formed the jury, we will now appeal to the executive through its head, his Grace the Duke of Buckingham. We are, yours truly,

ROBERT BOYLE & SON. 64 Holborn Viaduct, Jan. 2, 1885.

Our letter to Mr. Clark will be a partial reply to Mr. Banner's, which appeared in your last issue. We have now to say that, had we known at the time that Mr. J. P. Seddon formed one of the jury on ventilation, we should have lodged a formal protest against his acting in that capacity, on the grounds that he was declaredly antagonistic to us, and that he was also the advocate of another system

of ventilation (Mr. Banner's), upon which he would also have to adjudicate. Had we been invited to send our airpump ventilator for the purpose of being tested, which we were not, and had we been aware that Mr. Seddon was one of the jury, we should most certainly have declined. And it has yet to be explained why the names of the jurors were kept so strictly secret in spite of all our attempts to ascertain them.

With respect to the value of the tests, we have already, through the medium of your columns, expressed our opinion, and that opinion we not only maintain, but are prepared to prove, is correct. As to the efficiency of Mr. Banner's or any other ventilator, as compared with the air-pump ventilator, there is no surer or more crucial test than the test of time, and no better judge than the public. It is not for us to boast of how long our ventilators have now been in use, nor of the number of buildings, public and private, in almost every country in the world, which we have successfully ventilated, nor of the alm st incredibly large number of ventilators which we have sold during the last fourteen years. The fact that they are known and extensively used in every quarter of the globe is in itself, we think any reasonable and unbiassed person will admit, sufficient proof that the air-pump ventilators have been found to satisfactorily answer their purpose, or they would not have been so generally adopted. But that is not all. We recently made an appeal to the principal architects in the United Kingdom to be favoured with their experiences of our ventilating appliances, and we received, in immediate response, over 400 most valuable testimonials, amongst which are to be found the names of almost every leading architect in the kingdom. We humbly think that the testimony of gentlemen who all speak from extended practical experience, such as Mr. Arthur W. Blomfield, Mr. Arthur Cates, the late Sir Gilbert Scott, Sir William Thompson, Dr. B. W. Richardson, the late Professor Macquorn Rankin, &c., will have a little more weight with the public than the pottering experiments of a few amateurs, whose ideas on the subject are possibly as vague as their practical knowledge is limited. Mr. Banner is simply making a farce of a serious matter when he again offers his bellicose challenge to single combat' for 100l. a side, &c. Considering that he has now offered this challenge to almost every ventilator maker in the country, and we believe has been also himself challenged, we should have thought that by this time he would have seen the folly of his conduct, and the ridicule he was bringing on the cause of sanitary science by his treatment of it as if it were the 'prize ring.' If Mr. Banner is so very desirous that his name should be handed down to posterity as one of the great sanitary reformers of the present age, let him, instead of giving away his 100/. in the way he proposes, expend it in applying his system of ventilation gratuitously to one of our city hospitals or homes, and then invite his friends and the press to witness what he has done.

We can assure him that, if he does this, he will accomplish his desire, and at the same time have done a good deed, which will be doubly satisfactory.-We are, yours truly, 64 Holborn Viaduct, Jan. 2, 1885.

ROBERT BOYLE & SON.

Sir, From their letter on page 285, Messrs. Kite & Co. would have it to be inferred that their exhaust ventilators' were tested by Mr. Clarke at the Health Exhibition testing room; but, from all I can learn as yet, they had no 'ventilator' tested there, but only their chimney can! Consequently, while they might deserve the Gold Medal for their inlet and outlet ventilators-in the latter case their chimney breast ventilators being meant-it is a different matter to speak of winning the Gold Medal with an appliance which was never in the contest at all.

Kite's ventilator, with two vertical openings on the principle patented in 1846, is, in my opinion, a very poor exhaust appliance, and I said so several years since; and

this opinion is further confirmed by experiments lately made by me with said ventilator, as modified now by Messrs. Kite & Co. from the old diamond shape to a round section. On the other hand, I consider their chimney can, which I have also tested against my chimney can, to be a very good one. Yet, had I known that chimney cans were to be tested, and had sent in my own, Kite's might have been second instead of first. I say so because I tested both on December 27, when in six testings of one minute of each the one gave 1,328 feet of up-current, and the other 1,300 feet; the highest in one minute of the one being 308 feet, and of the other 320 feet, so that the two cans might be said to be six of the one and half-a-dozen of the other.

I also before this tested Kite's exhaust ventilator for a 4-inch soil-pipe against mine for a 3-inch pipe, the pipe of Kite's ventilator being only 34-inch bore to go inside the pipe, while the pipe of mine was 33 inches in diameter. The best result of each showed Kite's in four minutes 1,400 feet up; my one, 2, 140 feet up; plain pipe, 1,510 feet up.

I again tested Kite's 4-inch ventilator with its 3-inch pipe against my 4-inch one, with its 4-inch pipe to go over the 4-inch pipe. In this case the highest Kite's gave in one minute, with is shut side to the wind, was 470 feet, while the lowest my own gave was 750 feet. With its

open side to the wind, however, the highest of Kite's was only 150 feet a minute; the lowest of the plain 4-inch pipe was 370 feet a minute, and its highest 500 feet.

How does the result of these experiments bear upon or tally with the attempt made by Messrs. Kite to make the public believe that their exhaust ventilators had been tested at the Health Exhibition, and that they had got the Gold Medal therefor?

Gold Medals were given to three firms in the ventilating section, including a French and a German firm; but, as said section comprised a variety of appliances, it is quite possible the Gold Medal in no case had anything to do with wind-acting exhaust ventilators. An outlet ventilator into a chimney, or one acting by gas or machinery, has nothing to do with wind-acting ones. Glasgow, Jan. 3.

W. P. BUCHAN.

We should not have noticed this particular point any further, but for Mess s. Kite & Co.'s letter, which we feel somewhat surprised at after the confession they made. Now they say all right-thinking people will deprecate the attacks made on the jury and tester. Surely, after they have acknowledged theirs was a chimney-top and not a ventilator which was tested, they cannot wish the public to believe that the tester was a competent man to perform such a duty. Does it not show his utter incapacity to do so? In their letter they would have one and all overlook their previous letters, and give heed to the sympathy they offer to the man who undertook a duty, and by their own showing' was incapable of performing. We think the tester should have objected to the chimney-top being included in the list of ventilators. It was sent as a ventilator, it was tested as a ventilator, but it was not a ventilator. How was it, if everything was done conscientiously, this was not discovered by the judge? In our opinion it shows one of two things, either the incapacity or the inconscientiousness of the judge. Messrs. Kite & Co. say their chimney top or apparatus, which took the Gold Medal, was made on the same lines as their turret ventilator; so much more is the reason why the judge should have objected to it, as being wrongly entered. If A had a sailing yacht entered for a race, and B had a steam yacht built upon the same lines as the sailing yacht, would that entitle B to enter his yacht for the same race, simply on the plea that it was built upon the lines of a sailing yacht? Would not the umpire or the judge at the entering discover this before the race commences. If not, they would be unequal to the duty they undertake. Should it be overlooked, and all entered as sailing yachts, the race completed, and

the steam yacht came in first, then comes the questionIs she a sailing vessel, and entitled to the prize?' We wait for no answer to this question. Should the prize be handed over to the owner of the steam yacht, we think so much blame could not be attached to the recipient of the prize as the donor. We have said before, we do not begrudge any successful competitors their award; but we think we should have been spared the harassing remarks of 'without malice or favour,' for this fairly implies that all exhibitors must have had an equal chance. It is very easy for a prize-winner to use language so modest and becoming, but not so easy for one who has been refused a fair trial as we have been ;' and without the reason or explanation why we were so treated. To use the language of Messrs. Kite & Co., we are inclined to think the public will deprecate our lot, rather than facts made known of the jury and tester. As to the means so applied for testing, we say there is not a particle of truth in it; and we are in a position to prove it. There is a means of testing the merits of a ventilator as easily as a gauger can gauge a cask of spirits as to quantity and quality, which he can do to the greatest exactness by means of proper apparatus; but he might as well put a two-foot rule into the cask to find the strength as to put an anemometer into a ventilator to see what extracting power there is in it where a forced current is set up. Let anyone fix a ventilator, the bottom coming down into a room. make the air therein quiescent, and no natural element acting upon the outside of the ventilator: see what the result will be. In the case of the late testing all the natural element was cut off from the outside, and a forced current set up from the inside, which brought about a passing through the anemometer an amount of cold air, and whichever passed the most forced current was considered the most effective ventilator. Nothing can be more misleading. In proof of this take an instance that has within a week from this date been demonstrated in the following manner :-A 14-inch ventilator was fixed at the head of a grand staircase, with very large rooms at the foot of the stairs. To the ventilator were attached five injection tubes. At the ceiling line and at the bottom of the ventilator when the gas was alight, the temperature was 75°; the ventilator was passing, by the anemometer's register, 78,000 lineal feet of air per hour; this was then reduced to 60,000 feet per hour, and the temperature was also reduced to 62° and 65° maximum and minimum; that being so, when was the ventilator doing the work it was intended for? These facts lead us to the conclusion that we are right in what we have always said, that cold air passing through a ventilator is not only unreliable as to its merits, but to a great extent destroys the power of extracting hot air. Over and over again we have proved this to be the case, and in the presence of a commissioner to a trade journal, who took a great interest in the experiments made with ventilators. It was our

intention to have written a few letters upon the art of testing ventilators, but we are sorry to find that some of the trade journals who claim to be the leading organs have closed their columns to such articles, and thus deprived their readers of any information that they themselves are unable to give.

Sir, we feel sure your object always is to give space for matter upon scientific questions and to set the wronged righted, and you will therefore give space and insert this in your next issue, and oblige

EDGAR ALDOUS & Son,
Ventilating and Sanitary Engineers,
2 Elmhurst, Upton Lane,
Forest Gate, E.

Jan. 1, 1885.

A NEW DEPARTURE IN HOUSE DRAINAGE. Page 253 in the SANITARY RECORD for December bears the above title, and it is, I think, worthy of the attention of all who possess, or who aspire to have, authority in the design and execution of private sanitary work,

This is my opinion because I see in Mr. Ebbetts' work (there described) evidence of that thoughtfulness in the application of the principles which commended themselves to him which is indispensable to the attainment of satis factory results, but which, I believe, is not always sufficiently exercised.

My object in writing is, by calling attention to its im portance, to encourage such thoughtfulness, especially among the many new and earnest workers in sanitary science who are being brought forward by the growing demand in the public mind for good domestic sanitation. Is it not distinctly needful for such, indeed for all, sanitary workers to remember that an intimate knowledge of good principles, though necessary, is not by any means sufficient? What is urgently called for is thought in the appli cation of these principles to the conditions of each particular This thoughtfulness is clearly manifest in Mr. Ebbetts' paper, and it is a quality which finds ample room for exercise in the design and the carrying out of sanitary work where inattention to points of detail' may so easily prove disastrous, and may wreck the usefulness of an excellent general design.

case.

It is given to only a few workers to lay down principles which prove themselves worthy of general acceptance, but the honour of applying these well can be attained by everyone who makes it his purpose.

In writing this I am not to be taken as agreeing with all that Mr. Ebbetts says; in fact, I am unable to do so. It is not so much his scheme as his method of going about his work which is, I think, suggestive. But Mr. Ebbetts might reconsider whether the inspection holes' (which he shows) are called for on a drain which is straight, which is laid to a gradient of as much as 6 inches in 10 feet, which is terminated by a sweeping eye and by a chamber, and which is provided with a special flushing tank. He might also reconsider whether the waste-pipes of a housemaid's sink and bath, even if 'trapped,' should have been allowed to remain joined to a soil-pipe. But perhaps, in this case, Mr. Ebbetts had no authority to alter internal arrangements.

As to the design of the ventilation being 'new,' Mr. Ebbetts will find his principle laid down, and at least permitted, by the Model By-laws (issued by the Local Government Board) with respect to New Streets and Buildings,' clause 65, sub-section (¿) (¿). The details specified there are, however, somewhat different from those in the case described.

I do not write, however, with the view of criticising the paper in question, but from a strong wish to point out the great use of painstaking thoughtfulness in putting into practice good sanitary principles, and the wide scope which exists for its exercise by individual workers.

ALEXANDER A. KYD,

An Engineer of the London Sanitary Protection Association.

London, Dec. 31, 1884.

I have read with some interest Mr. D. J. Ebbetts' paper upon A New Departure in House Drainage,' in the SANITARY RECORD of December, because the principle he has applied, and advocates, is a child of mine, and I have applied it to a large number of buildings, and with

success.

:

If you refer to the proceedings of the Annual Conference at the Society of Arts, on National Water Supply, Sewage, and Health, May 15 and 16, 1879, p. 144, you will see a paper by me upon the double check system of house drainage, and I extract from it the following :"In the present day, every closet should be constructed so that it may be flushed by about two gallons of water; this quantity of water, if it were possible to be forced at once into the 4-inch soil-pipe, would form a solid piston of water, about a yard long, and would, in descending, push before it with considerable power the air in the pipes; and if the soil-pipe were 10 feet long, 10 feet of air would

be displaced, and forced out of the open end of the pipe, at the same time air would pass into the top of the soilpipe extension, and follow the water piston, so that during the time it was acting as a displacer of foul air, it would be filling the vacuum with fresh air; and, if I had not such an objection to mechanical valves, I could easily contrive one that would retain the yard of water in the soilpipe, which, being released suddenly, would act with very great power; but as in practice I have found it is desirable to lay on the water for pan-flushing by a large pipe, say 1 inch bore, taking care that the valve which allows the water to escape from the flush tank, and also the way into the closet-pan, be of equal capacity to the pipe; a good flush is procured, and the descent of water passing down the soil-pipe, acting in a zigzag and spiral form, produces an effect similar to the solid water piston described; and it has the advantage of being more gradual in its action, and thereby displacing more foul air than though it acted suddenly. All open-top soil-pipes, having no exit pipes, lose, to a large extent, this piston power for displacing foul air, and those having an opening near the ground (as in some systems) act as I have described, but with the disadvantage, that upon each occasion of the closet being used, a portion of foul air is forced out of such openings, and becomes in course of time very objectionable, producing at a low level disagreeable odours, and in the vicinity of our doors and windows. The double check

system has the advantage of being free from the objections I have pointed out. The soil-pipes and drains being open at either end, so that any foul air in them may be displaced, are easily acted upon, and I have found that a bucket of warm water thrown down a kitchen sink, has caused a current of air to circulate through the pipes; and a leaky water-tap, allowing a small quantity of water to pass down the drain constantly, has during the night, and at other times, caused a moderate flow of air in one direction, and also in the arrangement of pipes, when one pipe is at the back of the house, and the other at the front, should the sun shine upon one pipe, the heat produced will cause a free circulation so long as one pipe is warmer than the other. Of course, the various powers described do occasionally act one against the other; there may be times when the water piston would be forcing air in one direction, and the bucket of water in the other, but in practice this has but little effect upon the successful working of the system, for upon examination I have found the drain and soil-pipes very free from foul gases.'

By the above extract it will be seen that Mr. Ebbetts' scheme has been anticipated, an I may say that houses were re-drained by me upon this system as early as 1863, and last year I exhibited at the Health Exhibition, London, a drawing of the double check system. I take exception to some parts of his scheme, such as waste-pipes connected to the soil-pipes, and the rain-water pipe, because such an arrangement does occasionally untrap the waste-pipe traps, and then they become ducts for air to enter the house, such air being contaminated by passing through slimy ducts, and if drain-pipes are properly laid, I see no need of special flushing or sweeping ends.

It is very seldom a hot flue can be met with to fix an upcast shaft against; the idea, though, is a good one when you can apply it. HENRY MASTERS.

moulded to the shape of a quadrant of a circle-a curved drain-pipe in fact. It was used in the works referred to to connect the vertical with the horizontal pipe with an easy bend, and was mentioned in the article because such connections are generally made with traps, which interrupt the flow of the water besides producing other incon veniences.-D. J. EBBETTS.]

PATENT INSPECTION OR ACCESS-PIPES FOR HOUSE DRAINS.

On p. 279 there is illustrated and described, and also highly approved of, what is purported to be a new style of Access-pipe' for house drains, said to be invented by a Mr. G. C. Davies, of London. I doubt however, he is rather late in bringing this longitudinal opening on the top of the pipe with a lid for same as a new invention,' seeing that I got an award of merit for it at the International Medical and Sanitary Exhibition, London, 1881 ; and it has also received two or more certificates of merit from the Sanitary Institute of Great Britain since then. Toese Access-pipes were patented by me at the end of 1879, and I have used them since in a variety of ways at a number of buildings, while many architects have used them on their drainage works. I mention some in the fourth edition of my book on 'Plumbing and House Drainage,' published two years since. These pipes of mine can be made of any suitable material-fireclay, stoneware, iron, lead, &c. Sometimes iron lids are used with the fireclay ones.

It is a pity for Mr. Davies that he is too late, but I cannot help that. W. P. BUCHAN. Glasgow, Jan. 5, 1885.

WATER FILTERS.

Our criticism of the International Filter,' as we stated at the time, was not prompted by Mr. J. J. P. Sawyer's 'challenge,' which is beneath our notice, but by your editorial paragraph. However, not to appear discourteous, we will in a few words reply to your correspondent's letter in the last number of the SANITARY RECORD.

There is no novelty whatever in his filter as far as its general arrangement is concerned. Thus, 'Gray's improved self-cleaning rapid filter' is almost identical with the International,' excepting the cone-shape of the filtering medium. Mr. Sawyer's proposal to use for the purpose of the fight,' as he pleases to express it, not his patented material, but animal charcoal, is contrary to common sense, for if there is any use in testing a filter it can surely only be in the form in which it is offered to the public. Any filter containing, say, coarse gravel only, through which the water would pass without being in any way purified, would, we submit, produce results similar to those claimed in the challenge. For this reason we drew attention in our last letter to the omission in the lenge' of any distinct reference to the most important question, which is the purification effected by the filtration. Your correspondent's observations do not remove this, for one week submitted to other tests, with permanganate, &c.' (point 6), refers, as it stands, merely to a testing of the filtering medium, and not of the filtered water. Even should the latter have been intended, the phrase quoted is too vague to do away with our objection. A point II, to which he refers us with reference to the testing of the filtered water, does not exist, there being only ten points, as will be seen on p. 6 of your issue quoted above.

chal

Declining further correspondence on this subject, we remain, Sir, your most obedient servants, The Spongy Iron Filter Company, Purveyors to the Queen by appointment.

22 New Oxford Street, W.C. Jan. 2, 1885.