fresh portions of material and prepare it for combustion. The mass is reduced in bulk to one-third. Other refuse, such as condemned food, vegetable garbage, street sweepings, and the like, are reduced to charcoal in another apparatus called the Carbonizer. The carbon thus produced is used for disinfecting purposes, for decolorizing the waste water from factories, etc. The excreta proper it is proposed to collect in pails .and reduce to small bulk, by drying in a closed apparatus, called the Concretor; the ammonia being fixed by the sulphuric acid fumes produced by the other processes. By this means the contents of the pails are reduced to one-twelfth, and a valuable manure obtained, which may be either in the form of poudrette or mixed with a little charcoal.

The Pneumatic Air Plan' (Aspiration Plan).

A Dutch engineer, Captain Liernur, proposed some years since an entirely novel plan. No water or deodorizing powders are used; the excreta fall into a straight earthenware pipe, leading to a smaller iron siphon pipe, from which they are extracted periodically by exhaustion of the air. The extracting force which can be used (by an air-pump worked by a steam engine), is said to be equal to a pressure of 1,500 tb per square foot, which is sufficient to draw the excreta through the tubes with great rapidity. The plan has been tried on the small scale at Prague, Rotterdam, Amsterdam, Leyden, and Hanau, also at Brünn, Olmutz, and St. Petersburg, and the opinions concerning it are very various. It does not render sewers unnecessary; indeed, the system contemplates an arrangement of sewers for slop and other waters.

Shone's Ejector System. This is an opposite plan to Liernur's, the agent

The Sewage Question, by F. C. Krepp, London, 1867. This book was written for the purpose of bringing the Liernur plan before the public, and some parts of it must be taken with limitation.

Reports in Deutsche Vierteljahrs. für öffentl. Gesundsheitspfl., Band iii., p. 313 (1871).

Ibid., Band iii., p. 312.

Report of Kauff and Esser, in Deutsche Viertelj. für öff. Gesundsheitspfl., Band iv., p. 316. These gentlemen were sent from Heidelberg to investigate the plan. Reports of Messrs. Schröder and Lorent (Ibid., Band iv., p. 486). In this Report is a good technical and financial account.

Ballot (Medical Times and Gazette, February 15, 1873) spoke favorably of it, and considered it to have been a decided success in Amsterdam and Leyden. Gori, on the other hand (Med. Times and Gazette, March 8, 1873), replied to Ballot, denied that this is the case, and declared that in Amsterdam all with one consent say, "It is impracticable." Ballot adheres, however, to his statement.

I saw the system at work in Leyden in September, 1876, when much of its results and details was explained to me by the late Professor Boogaard, and again in Amsterdam in 1879, with Captain Liernur himself. It seemed very effectual, and there was a total absence of odor, although I was present in some of the closets at the moment that the contents were sucked away by the apparatus. In Leyden the material is sold in barrels in the liquid form; but at Dordrecht, where the newest and most complete works are, it is made into poudrette, which is said to pay. In this country, Mr. Adam Scott has done his best to bring it to public notice (see his papers in the Builder, Sanitary Record, Public Health, etc.). He considers that it has been shown by five years' experience in Holland, that the pneumatic system, by removing excrement without any possible pollution of air, soil, or water, has banished typhoid and diphtheria, as well as cholera and any diseases that are conveyed by the discharge from the intestines. The Committee on Town Sewage (Mr. Rawlinson and Mr. C. S. Reade) speak most disparagingly of it, more so, indeed, than seems warranted by all the evidence. On the other hand, the patent for Austria and Hungary has been purchased by the Vienna Joint-Stock Agricultural Society, who consider it a success, both hygienically and financially.(F. de C.).

being compressed air instead of exhaustion. It has been applied at Wrexham and at Eastbourne, and is well spoken of.

COMPARISON OF THE DIFFERENT METHODS.

Much controversy has arisen on this point, though it does not appear that the question of the best mode of removing excreta is really a very difficult one. It is simply one which cannot be always answered in the same way.

It will probably be agreed by all that no large town can exist without sewers to carry off the foul house water, some urine and trade products, and that this sewer water must be purified before discharge into streams. The only question is, whether fecal excreta should also pass into the sewers.

It will also be, no doubt, admitted that no argument ought to be drawn against sewers from imperfection in their construction. The advocate of water removal of solid excreta can fairly claim that his argument presupposes that the sewers are laid with all the precision and precaution of modern science; that the houses are thoroughly secured from reflux of sewer air; that the water-closets or water-troughs are properly used; and that the other conditions of sufficient water supply and power of disposal of the sewer water are also present. If these conditions are fulfilled, what reason is there for keeping out of the sewer water (which must, under any circumstance of urban life, be foul) the solid excreta, which, after all, cannot add very greatly to its impurity, and do add something to its agricultural value?

That it is not the solid excreta alone which cause the difficulty of the disposal of sewer water is seen from the case of Birmingham. That town is sewered; it contains nearly 400,000 inhabitants, and is in the greatest difficulty how to dispose of its sewer water; yet the solid excreta of only 6 per cent. of the inhabitants pass into the sewers, while the solid excreta of the remainder are received into middens.' The problem of disposal is as serious for Birmingham as if all the excreta passed in.

That great difficulty, in fact, consists not so much in the entrance of the solid excreta into sewers, as in the immense quantity of water which has to be disposed of in the case of very large inland towns with waterclosets. If water-closets are not used, the amount of water supplied to towns, and that of sewer water, are considerably lessened.

Looking to all the conditions of the problem, it appears impossible for all towns to have the same plan, and the circumstances of each town or village must be considered in determining the best method for the removal of excreta. London is particularly well adapted for water sewerage, on account of the conformation of the ground north of the Thames, of the number of streams (which have all been converted into sewers), and of the comparative facility of getting rid of its sewer water. The same may be said of Liverpool and many other towns. In Birmingham, on the other hand, the inland position, the price of land, and the comparative difficulty of getting water, seem to render other plans more desirable. If it had been possible, years ago, to act with our present knowledge, and to devise a scheme for Birmingham, it would have been best to have taken the rain

1 Report of the Birmingham Sewage Inquiry Committee (1871), Summary, p. 11. It should, however, be added that two-thirds of the middens drain into the sewers, i.e., allow urine and some diffluent fecal matter to pass in. In 1875, 128,512 tons of midden refuse were removed and sent to country depôts, to be afterward disposed of to farmers.

fall into the Rea; to have had the sewers merely for house and trade water (which would have given a manageable amount for filtration through land); and to have introduced some deodorizing dry plan for the solid excreta, and for a part of the urine, with short periods of removal.

In many towns where land is more available, the immediate application to land, either by filtration or irrigation, may be evidently indicated by the conditions of the case, while in others precipitation may have to be resorted to before application to land. It does not appear that precipitation should in all cases precede irrigation or filtration, though mechanical arrest of the large suspended matters is necessary. There may be some towns, again, in which the impossibility of getting water or land may necessitate the employment of dry removal; and this is especially the case with small towns and villages, where the expense of good sewers and of a good supply of water is so great as to render it impossible to adopt removal by water. It may, indeed, be said that, in small towns in agricultural districts, the dry removal, if properly carried out, will be the best both for the inhabitants and for the land.

The view here taken that no single system can meet all cases, and that the circumstances of every locality must guide the decision, is not a compromise between opposing plans, but is simply the conclusion which seems forced on us by the facts of the case. It does not invalidate the conclusion already come to, that, where circumstances are favorable for its efficient execution, the water sewage plan (with or without interception of rainfall) is the best for large communities.

CHAPTER XI.

WARMING OF HOUSES.

THE heat of the human body can be preserved in two ways:

1. The heat generated in the body, which is continually radiating and being carried away by moving air, can be retained and economized by clothes. If the food be sufficient, and the skin can thus be kept warm, there is no doubt that the body can develop and retain its vigor with little external warmth. In fact, provided the degree of external cold be not too great (when, however, it may act in part by rendering the procuring of food difficult and precarious), it would seem that cold does not imply deficiency of bodily health, for some of the most vigorous races inhabit the cold countries. In temperate climates there is also a general impression that for healthy adults external cold is invigorating, provided food be sufficient, and if the internal warmth of the body is retained by clothing.

2. External heat can be applied to the body either by the heat of the sun (the great fountain of all physical force, and vivifier of life), or by artificial means, and in all cold countries artificial warming of habitations is used.

The points to determine in respect of habitations are— 1st. What degree of artificial warmth should be given?

2d. What are the different kinds of warmth, and how are they to be given?

SECTION I.

DEGREE OF WARMTH.

For Healthy Persons.-There appears no doubt that both infants and old persons require much artificial warmth, in addition even to abundant clothes and food. The lowering of the external temperature, especially when rapid, acts very depressingly on the very young and old; and when we remember the extraordinary vivifying effect of warmth, we cannot be surprised at this.

For adult men of the soldier's age, who are properly fed and clothed, it is probable that the degree of temperature of the house is not very material, and that it is chiefly to be regulated by what is comfortable. Any temperature over 48° up to 60° is felt as comfortable, though this is dependent in part on the temperature of the external air. It seems certain that for healthy, well-clothed, and well-fed men we need not give ourselves any great concern about the precise degree of warmth.

For children and aged persons we are not in a position at present to fix any exact temperature; for new-born children a temperature of 65° to

70°, or even more, may be necessary, and old people bear with benefit a still higher warmth.'

For Sick Persons.-The degree of temperature for sick persons is a matter of great importance, which requires more investigation than it has received. There seems a sort of general rule that the air of a sick-room or hospital should be about 60° Fahr., and in most Continental hospitals, warmed artificially, this is the contract temperature; but the propriety of this may be questioned."

There are many diseases greatly benefited by a low temperature, especially all those with preternatural heat. It applies, almost without exception (scarlet fever?), to the febrile cases in the acute stage, that it is desirable to have the temperature of the air as low as 50°, or even 45° or 40°. Cold air moving over the body is a cooling agent of great power, second only, if second, to cold effusion; nor is there danger of bad results if the movement is not too great. The Austrian experiments on tent hospitals show conclusively that even considerable cold is well borne. Even in the acute lung affections this is the case. Pneumonia cases do best in cold wards, provided there is no great current of air over them. Many cases of phthisis bear cool air, and even transitions of temperature, well, provided there be no great movement of air. On the other hand, it would appear that chronic heart diseases with lung congestion, emphysema of the lungs, and diseases of the same class, require a warm air, and perhaps a moist one. With respect to the inflammatory affections of the throat, larynx, and trachea, no decided evidence exists; but the spasmodic affections of both larynx and bronchial tubes seem benefited by warmth.

In the convalescence, also, from acute disease, cold is very badly borne ; no doubt, the body, after the previous rapid metamorphosis, is in a state very susceptible to cold, and, like the body of the infant, resists external influences badly. Convalescents from fever must therefore be always kept warm. This is probably the reason why it is found inadvisable to transfer febrile patients treated in a permanent hospital to convalescent tents, although patients treated from the first in tents have a good convalescence in them, as if there were something in habit.

SECTION II.

DIFFERENT KINDS OF WARMTH.

Heat is communicated by radiation, conduction, and convection. The latter term is applied to the conveyance from one place to another of heat by means of masses of air, while conduction is the passage of heat from one particle to another-a very slow process. Practically, conduction and convection may be both considered under the head of convection.

1 It is singular, however, that in some old people the temperature of the body is higher than normal (John Davy). Is there, then, a difference in the amount of external heat required in different persons?

* It is owing to this rule that in French hospitals, artificially ventilated and warmed by hot air, the amount of air is lessened and its temperature heightened in order to keep up the contract temperature of 15° C. (= 59° F.) The air is often then close and disagreeable. A safe general rule is never to sacrifice fresh air to temperature, except in the most extreme cases. Of course, cold currents of air are to be avoided if possible, but it is safer, as a rule, to let the general temperature go down, rather than diminish the change of air. In most cases it can be compensated for by additional covering.

* See Report on Hygiene in the Army Medical Reports, vol. iv., by Dr. Parkes. The Prussians have also lately made great use of tents in the summer.