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in many ways was very great. Formerly, at home, he hadpractically eaten nothing and cared only to stay in bed. Henow ate and drank all that was given him, and was alwaysready to rise from bed in the afternoon. After six days hisblood count was as follows : Red corpuscles, 5,100,000 perc.mm., or 102 per cent. ; white corpuscles, 3000 per c. mm.The general improvement was, however, not maintained.He had to return home, and gradually the disease obtainedthe upper hand.

Pernicious anaemia, of course, shows remarkable remissions,but the rapid improvement in the blood count after the hypo-dermic treatment seems to hold out some hope for the casesof younger and more vigorous patients, especially if it werebegun soon enough. I did not see my patient until the casewas at least four months advanced according to history, andquite possibly more.-I am, Sir, yours faithfully,East Meon, Hants, February, 1911- EDWARD T. JONES.EDWARD T. JONES.

EXPERIMENTS IN SEWER VENTILATIONAT LEICESTER.

(FROM OUR SPECIAL SANITARY COMMISSIONER.)

Leicester, February, 1911.MORE than eight years have elapsed since a detailed

description was given of an ideal method of ventilatingsewers. 1 At that time the system had not gone beyond thetheoretical and laboratory stage. The chief fault then foundwas that it all seemed too good to be true. Now it is

possible to speak differently, for the method has been appliedduring a sufficient number of years and to a large enoughdistrict to be judged from the practical results obtained.The object of the system is to prevent the ventilation ofsewers in the streets or by soil-pipes on the tops of thehouses. Further, greater care is displayed to prevent theintercepting traps placed between houses and sewers becomingsmall cesspools and to ensure more efficient ventilation ofthe small branch drains. A vigorous current of air may passalong the straight sewer in the street and yet have butlittle or no effect on the small tributary drains thatcome from behind the houses and down passages. The

only way to ensure ventilation throughout is to placethe inlets or outlets at the extreme ends of the piping.Thus there is the school of sanitary engineering that wouldhave no intercepting trap between the house and the sewer,and by carrying every soil-pipe to the roof of the housesconvert them all into sewer ventilators. The air would thenhave to travel the whole length of the domestic drains to getout, and there would be no neglected corners or branchdrains. The ventilation of private drains and public sewerson the roofs of dwelling houses and within a few feet ofbedroom windows is not, however, a very satisfactoryexpedient. To say that the sewer air will be blown awayis not a sufficient assurance. When a neighbouring chimneycatches fire the odour, and even the smoke, is blown down tothe street level. Sometimes the smoke from one chimney isblown down the chimney of another house, invading, muchto the surprise of the inhabitants, a room which has no fire ;and where the smoke goes the air from the soil-pipes willfollow.

Air Needed Per Head in Sewers.

To meet these and many other objections it has been proposedto reverse the process and not allow any air to escape fromthe soil-pipes; but, on the contrary, to draw air downthese pipes to the domestic drains and into the sewers. Herethe air would be conveyed to a spot where it could betreated or safely discharged. For this artificial poweris necessary, and that constitutes the first and probablythe chief objection to the whole system. There is an in-stinctive dislike to the employment of machinery, basedprobably on the too frequent experience that machineryis apt to get out of order. It is therefore a good pointin favour of a mechanical system if it can be shown that, inthe event of a breakdown in the machinery, no very injuriousconsequences would ensue. Of greater importance thanarguments for or against machinery is the dominating factthat in ventilating it is absolutely impossible to ensure a

stable result except by the use of machinery. Just as

1 See THE LANCET, August 9th, 1902, p. 405.

the weather varies, so does natural ventilation vary, andthis precisely in the opposite direction to our require-ments, giving violent draughts in cold weather and hardlyany movement of the air when it is hot and sultry. In

dealing with this problem Mr. I. Shone had the advantageof experience as a mining engineer, where the entireventilation must be artificial, though the breakdown ofmachinery might involve a serious loss of life. There wasno hesitation, therefore, in proposing to base the ventilationof sewers on the revolutions of a fan so as to provide in allweathers exactly the volume of air required to keep theatmosphere within the sewers and drains so fresh as to beuniniurious. What this amount would be has been explainedby others writing on this subject. Dr. Letheby had madeexperiments on the gases engendered by putrid sewage,and the results were that one cubic foot of fresh air everytwo minutes would suffice to dilute the air escapingfrom the 30 gallons, or normal daily flow of sewageper inhabitant. In other words, for every inhabitant 30 cubicfeet of fresh air must be drawn every hour into the soil-pipeof the house inhabited. Obviously this cannot be done withany degree of certainty except by mechanical appliances.Having obtained this figure it was further possible tocalculate that at 3d. per Board of Trade electric unit a" I Sirocco fan could be worked so as to provide the requisiteamount of air for 1- 41d. per annum per head of the population.

The Need of Cubio Measurements.The next point was to devise means to insure that the

regulation amount of air should penetrate every soil-pipe,whether near or far from the fan. This seemed more easy todo in theory than in practice, and experience has proved theaccuracy of this criticism. Originally a very elaborate inletwas provided, regulated by a vulcanite screw plug which hada small hole pierced in the centre. The size of the hole, insome places barely big enough to let a lead pencil through,varied according to the suction within the pipe, beingsmaller the nearer the house stood to the extraction fan.These and many other details were given by me in thefirst description of the system which appeared in thesecolumns, and it is not necessary to go over the same

ground again. But we have to see how far the original planhas been modified in actual application. That such experi-ence has now been acquired is due to the enterprising spiritof the highway and sewerage committee of the LeicesterCorporation. They determined to apply the system to anarea of two and a half acres consisting of streets 40 feet widewith 80 six-roomed houses of the artisan class, and a popula-tion of 356 persons, or an average of 4’ 45 persons per house.The foul water sewers it was proposed to ventilate were 297yards long. There is a totally separate system for storm andrain water from the surface of the streets and the roof of thehouses. To convey the sewage proper there is a 12 inch pipesewer 202 yards long and two short branches at right angles.The sewers to which the new system is applied dischargeinto a brick main of 3 by 2 feet, from which they aredisconnected. At the junction the pipe sewer is carefullyseparated from the main sewer by a deep dip trap. Thedrains that connect the dwellings with the 297 yards of pipesewers measure in all about 583 yards and are mostly6 inches in diameter, while the branches to the closets andsink wastes are 4 inches. The smaller half of these have claypuddle joints instead of Portland cement for the joints. A4 inch diameter cast iron pipe is added to the soil pipe andcarried to the roof. It becomes a ventilator, but there areonly 27 such ventilators to the 80 houses, in some cases sixhouses being connected with the one upright pipe ventilator.The cubic capacity of all these house pipes and drains is304 cubic feet, that of the public sewer 661 cubic feet, so wehave to deal with a total of 965 cubic feet, and it would take6021 gallons to fill this with water. Now when a part of thesedrains and sewers were submitted to a water test it becameapparent that there was a considerable leakage, amountingto seven gallons per minute. Here, then, was the firstobstacle, the first great difference between the theoryas demonstrated by laboratory experiments and actualapplication.

Leakage Upsets all the Calculations.At the highest point in the district a chamber was con.

structed under the causeway and here a I I Sirocco " fan, 15inches in diameter, driven by an electric motor capable of pro-ducing 700 revolutions per minute, was introduced. On one

619

side the chamber is connected with a flushing manhole andthe air is drawn out of the sewer by the fan. On the other sidethe air thus extracted is forced into a ventilating shaft40 feet high. When all was completed a five days’ test wasmade. The velocity of the air entering the 27 soil-pipeinlets was measured by anemometers and the result showedthat more air was pumped out through the extract ventila-ting shaft than had entered the sewers by the proper inlets.Therefore the leakage which had enabled some of the waterto escape when the water test was applied now allowedsome air to penetrate the sewers and drains. Thus the idealcalculations which, as said before, were all too good to betrue are now upset. Given absolutely air-tight sewers anddrains, with inlets all accurately measured and a fan revolv-ing with mathematical precision, every soil-pipe would havereceived exactly the number of cubic feet of fresh air needed.But here was an unknown volume of air penetrating fromunknown places and upsetting all these precise calcula-tions. The mechanical part alone worked satisfactorily.The fan pumped out of the sewer exactly the right amountof air, only it did not appear that this air came from thefarthest as well as the nearest inlets. At these inlets-thatis to say, at the top of the 27 soil-pipes which are prolongedto the roofs of the houses-it was found, in some instances,that there was no perceptible current of air. It is true thatair must travel at the rate of 30 feet per minute before it hassufficient force to move the anemometer, but the amountentering at a slower rate than this is hardly worth includingin any calculation.

FiG. 1.

A cowl, constituting an air-inlet, placed on the top of the soil-pipes. The door-like opening can be seen which is used forintroducing the anemometer.

Under the existing circumstances, short of re-laying all thehouse drains and the sewers in such a manner as to makethem absolutely air-tight and keeping them in that conditionfor ever, a totally new set of calculations had to be made.Nor could any theoretical basis for such a reckoning be ’’

found, for no one could tell the extent of the leakages with ’iwhich it was necessary to deal. Therefore, experiments hadto be made with all the air inlets. Obviously much more airmust be extracted so as to maintain a current through all thesoil-pipes and also carry away what the leakages supplied.The minute and elaborated air inlet was too delicate aninstrument for this rougher procedure. After trying manymodels the present system was adopted. It consists of acylinder fitting over another cylinder. Both these havevertical apertures or slits, and the outer cylinder can betwisted round. If the apertures are made to fit over eachother we have the maximum opening, but by slightly movingthe outer cylinder the openings are rendered smaller andsmaller till they are closed altogether. This is covered overby an ornamental hood or cowl to keep the rain off (Fig. 1).

Underneath there is a commencement of piping which fits onthe top of the soil-pipe, and here is the space for a smalldoor large enough to admit a hand holding an anemometer.Thus it is necessary to place a ladder against the wall, toclimb up and introduce an anemometer into this aperture.If the record shows that the amount of air descending thesoil-pipe is insufficient, then the cylinder above must beturned round so as to enlarge the inlets. This descent ofthe air will vary from soil-pipe to soil-pipe according to itsposition and proximity to the extraction fan. Thus there isno rule, but a separate experiment must be made in eachinstance. This may seem complicated, but the needful

procedure shows that the system deals with realities. Accord-ing to the experiments made and the report of the boroughengineer, Mr. E. George Mawbey, M.Inst.C.E., the 27 inletsmeasured at first only 10,278 square inches, and this mighthave sufficed had the sewers been absolutely air-tight. Theinlets had to be increased to 75,258 square inches, and thesix-inch diameter extraction shaft was replaced by a nine-inch pipe. Thus the inlet space was equal to 89 per cent.of the outlet space given by the nine-inch extraction shaft.The working showed that 752 cubic feet of air were dischargedper minute by the fan into the extraction shaft ; but of thisonly 325’ 53 cubic feet, or a little less than half the totalvolume extracted from the sewers, entered the sewers

through the 27 soil-pipe inlets. In these ventilatingsoil-pipes of four-inch diameter the average velocity ofthe air was 226’2 feet per minute, representing an

admission of 12’02 cubic feet per minute, or 5’23 cubicfeet per house per minute, which is more than neces-

sary. Therefore, the fan was utilised to ventilate a

neighbouring sewer outside of the area devoted to the

experiment. This reduced the volume of air extracted fromthe sewers and drains of the area to 142 cubic feet perminute, and of these 106 - 08 cubic feet were admitted throughthe 27 soil-pipe inlets, giving an average per house of 1. 73cubic feet per minute. This is a magnificent result, for in24 hours the air within the house soil-pipes and drains ischanged 502 times and replaced by air drawn from the out-side atmosphere once in three minutes. Within the streetsewers the air is changed about 309 times in the 24 hours,or once in four and a half minutes.

The Chemical Test.The result thus achieved, it must be borne in mind, is

absolutely independent of all climatic conditions. The windmay blow or not blow from any point of the compass, thetemperature may fluctuate from the extremes of heat or cold,but still pure outer air penetrates the highest point of the soil-pipe, travels down to the lowest, then on to the sewers, bearingaway all noxious effluvia and preventing any accumulation orstagnation. The sewage, if foul, is constantly swept overwith fresh air ; there is not time for mischief to accrue. Thisis confirmed by chemical analyses. Outside, but close to thearea, analyses were first made of the air in the street, and itcontained 3’55 parts of carbonic acid gas per 10, 000 parts.In the sewer the air contained in the best samples 15’95 andin the worst 24-98 parts of carbonic acid gas per 10,000parts of air. When, however, the nine-inch extraction shaftwas applied and the system in the selected area was in work-ing order the air in the principal street of this area was

found to contain 3-18 parts of CO2 per 10,000, and within thesewers the average throughout the system was 9’ 59 parts ofCO2 per 10,000 parts. On another occasion the average wasonly 8-08, and after that it fell to 7-04 parts of CO2 per10,000 parts. Thus there can be no doubt but that thesewer atmosphere is purified by this system of ventilation.Finally, if the air from the sewer is discharged in the street,though, of course, at as high a level as possible, it will notprove as injurious as the ordinary sewer airs, which, it hasbeen seen, contain a much larger proportion of carbonic acidgas and whatever other impurities the excessive quantity ofthis gas may indicate or favour.

Tlte Advantages Secured.To fully appreciate these advantages it is necessary to bear

in mind that at present in most cases the sewer airs travel upfrom the sewers to the houses, escape by numerous leakages,and are discharged either through grids into the streets orthrough various ventilating shafts, many placed againsthouses and near windows. Thus the current is always fromthe sewer to the street or the dwelling. But with mechanicalpower to produce a vacuum in the sewers the current is

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reversed. Even if the sewers are badly built, if the drain-pipes are insecurely jointed, then it is pure outside air thatis drawn through these leakages into the drain or sewer, andnot foul air from drain or sewer that ascends and permeatesthe surrounding soil or dwelling. There remains, however,the old objection that all this is due to a mechanical appli-ance which may get out of order. If the fan is worked byan electric motor the electric current may he stopped by anaccident or by a strike. In that case no more disastrousresult would ensue than that of having to revert to the

system of ventilation now actually applied in most towns.The inlets would once more become outlets. The worst thatmight have to be done would be to remove the cowl inletsthat are on the top of the soil-pipes so that the latter mightmore readily become outlets till such time as the ventilatingfan could be set in motion and the system re-established.

The Intercepter Trap and other Obstacles.There is one more consideration. In many places there

are intercepting traps between the house drains and thepublic sewer. How, then, can the air be drawn down thehouse drains into the sewer without forcing the water sealof these intercepting traps ? For this purpose a specialintercepter has been invented, and it is applied in one

instance at Leicester to show how it works. (Fig. 2.) On

Fm. 2.

Paton-street, Leicester. Plan of chamber containing Messrs.Shone and Cutt’s patent intercepting trap. a, Drain betweenintercepter and sewer. B, Drain from house to intercepter.(Of course any inlet for fresh air purposes into the house-drain B, as would be necessary under the London CountyCouncil by-laws, would require further calculations againstthe admission of the extra air.) c, Shaft for passage of airfrom house-drain to sewer. D, Shaft for passage of air fromhouse-drain to E, box holding the suspended valve which Ionly permits air to pass from house to sewer.

each side of the water seal there is a small opening where apipe can be introduced and carried over to the other side ofthe water seal. Between the two a space is reserved where avalve is suspended in such a manner as to open and let airthrough from the house to the sewer, but the greater thepressure of air from the sewer towards the house the tighterthis valve would be closed. It is very similar to the inter-cepting trap which was proposed for use in carrying out thedrainage scheme for Cairo, and was described with illus-trations in these columns of May 8th, 1909 (p. 1350).For several years now this the Shone system of sewer

ventilation has been working in Leicester. No accident hashappened. It has given general satisfaction. The chiefobjection is the cost of the power that must be employed,not necessarily electricity ; but all power is more or less

expensive. On the other hand, the perfection of the resultsattained is worth a small outlay, and at the worst the costis not great. The second objection is that the system cannotbe applied like a ready-made suit of chthes. It represents,

on the contrary, the highest art yet attained in this direc-tion, and therefore requires to be tried on and fitted carefully,with intelligence and knowledge of the object to be realised.But when was a real scientific problem solved otherwise?The desire for simplicity may be exaggerated. The first

sailing boats had very simple sails and rigging, but they didnot sail far or quickly. The first sewers were also of verysimple construction, but the greater frequency of epidemicsin their days did not speak well for their sanitary qualities.

MANCHESTER.

(FROM OUR OWN OORRESPONDENT.)

The Manchester Hospitals.THE financial position of the Manchester hospitals is

becoming serious enough to cause great anxiety as to thefuture. The Royal Infirmary, the leading medical charity,"one of the finest infirmaries in the world," as Sir WilliamCobbett said at the annual meeting of trustees the other day,with its very complete equipment, must live far beyond itsincome if it is to be used to its full capacity. To meet theexpenses of the past year the board of management had towithdraw 11,944 from unappropriated capital," and, ofcourse, this depletion of capital cannot go on indefinitely.Sir William Cobbett said that energetic action was requiredto improve the position. One solution was to close 168 beds,so reducing the number to 315, or only about 25 more thanthe number in the old infirmary. A second was " to pay eachdeficiency of income as it arose, out of capital." Each ofthese schemes was so objectionable as to be out of court. SirWilliam Cobbett said the only proper and reasonable solutionwas to increase the number of the subscribers and the amountof the annual subscriptions, " as many of the subscribers mustbe in a position to give more than they did." As he said, asmall increase per subscriber would make an enormous differ-ence to the income. Sir William Cobbett had not the slightestdoubt that the money could be found, not only for the needsof the infirmary but also for those of the other local hos-pitals. The report, in addition to other matters, stated thedecision of the board to appeal for 2500 for the establish.ment of a special laboratory for the work of cancer research,and mentioned likewise that the number of persons who hadreceived the benefits of the charity during the year was67,827. Unfortunately, it may be said, with very little

qualification, that all the hospitals in Manchester andSalford are in a more or less similar financial condition.Their medical and surgical work increases by leaps andbounds, but it is not so with the subscriptions. Patients flockto the hospitals in crowds, and the question naturally arises,Ought all these people to be treated gratuitously? Thenew hospital of the St. Mary’s Hospitals, in Oxford-road,close to the infirmary, which has stood empty for some yearsowing to lack of funds, is to be properly equipped andopened in April next. It will be a great boon to women andchildren, but if the work is to be well done an increase inthe subscriptions of several thousand pounds a year will berequired.

Ashton Inflrinary Jubilee.The infirmary of Ashton-under-Lyne is to have its jubilee

in the coming spring, and an effort is being made to raise,c6000. Of this sum ,c4000 are required to clear off a debt,and the Z2000 will be used for the further equipment of theinfirmary. Up to the present over E2000 have been sub-scribed. In addition to the special appeal of the governorsthe workpeople’s committee has decided to raise .&1000 in

sixpences-40,000 sixpences-and this fund is rapidlymounting up.

Low Death-rate at Stalybridge.The Lancashire and Cheshire manufacturing towns do not

pretend to be attractive as health resorts ; but, as a rule,perhaps their reputation is lower than they deserve. How-ever this may be, Stalybridge has been pluming itself on thelast quarterly report of the medical officer of health, whichshows that the births were 124 (rate 17 0) and the deaths106 (rate 14- 5). This, said the chairman of the sanitarycommittee, was the lowest death-rate for some time past,and " was a most marked and gratifying reduction for thewinter months," and knocked on the head " the old sayingthat a green Christmas meant a fat churchyard. He said