media, or are conditions of life in which the germs are compelled

to grow.

Fifth. Sunlight is a powerful, natural attenuating agent.

Sixth. In the light of these facts I feel justified in the belief that there are other natural means of attenuating the micro-organisms of disease, and, in this way, of modifying the type of epidemics, or of preventing their development.

The environmental conditions, for example, of cleanliness of the person, of the home, and of the municipality; of pure air in the home, the office and place of business, in the schoolroom, church, and in all places where people congregate and germs find a breeding place; of drainage, temperature, humidity, altitude and climate, are believed to be very important factors in determining the growth and the physiological capacity of germs to manufacture disease-causing poisons.

I also recognize, but will not discuss at this time, the influence of environment in effecting the individual resistance to disease; the important rôle of mosquitoes and other insects in transmitting the germs of disease from the sick to the well, and the possibility that they, under certain unknown conditions, may, themselves, attenuate the germ they transmit, and in this manner may modify the type of the disease thus caused.-"Texas Medical Journal," January, 1904.

CIDER AND JAM IN ENGLAND.-During the past two or three years there has been a great revival of the cider trade. Cider is now being recommended by doctors for rheumatism and gout, and it has become quite a popular drink. The cider of England is usually very good, and is attractively put up. There is no reason why the United States should not get a good share of this trade. It is said that much of the cider for this season's consumption will be made from Canadian apples; in some cases, the apples being cut up and dried in Canada and sent to Devonshire and Herefordshire and submitted to a process to produce "homemade" cider. The jam trade in England is suffering from the increased price of sugar and the failure of the English fruit crop. Jam pulp is being sent from Canada to be put up by local manufacturers, and a large trade in French and German jams is expected. James Boyle, Consul, Liverpool, England, October 6,

PROTECTION OF WATER SUPPLIES.

THE LINES OF DEFENCE.*

By J. CARTWRIGHT, M. Inst. C. E., Bury.

In recent years, in connection with matters of water supply, the tendency with large communities has been to go further away from the place of consumption, and this course is being rendered increasingly imperative, owing to the growth of the population.

For those towns which can afford to go considerably beyond, to the uninhabited areas, this problem is not so acute, for at present there are nearly 4,000 square miles of wholly uninhabited land in large connected areas in England and Wales, of which 1,400 square miles are found in the mountains of Wales, a like area in the higher moorlands of the Penine chain, and 300 square miles in the Lake District. Over the whole of this area there is a very heavy rainfall, and the districts in question are well adapted for use as gathering grounds; the remainder of the ground is partly high land on the chalk and limestone ranges of southern and eastern England, partly fen and alluvial land, which is comparatively useless for gathering ground-chiefly on account of its low level -and a considerable portion of those eligible areas have already been secured for existing and projected waterworks. But for many authorities the only available sources of supply are not so favorably situated. The land from which the water is collected is largely arable, or, it may be, is sparsely inhabited, and to abandon the works which have been constructed and developed at considerable cost from time to time, as occasion arose, and go elsewhere, is altogether impracticable. Too often, in the past, sources of supply have been selected without any special regard to the character of the land over which the water flows, and very frequently drainage areas have been fixed upon rather on account of their proximity to the district to be supplied, or to their available yield, than on the quality of the water obtainable.

Before expressing an opinion as to the best means of protecting our water supplies, it is, perhaps, necessary that I should point out the possible sources of pollution from which they require to

*Presidential Address before the Manchester Association of Students of the Institution of Civil Engineers, November 18, 1903.

be protected. It has been proved that at altitudes where high clouds form, the atmosphere is so pure that rain water may be considered as being normally free from bacteria and chemically pure, and that it is only when it passes through the lower atmospheric strata, over inhabited districts, that contamination begins. However uninhabited the watershed may be, and the freedom from bacteria which the rain may possess, when it reaches the surface of the ground it immediately becomes liable to pollution of various kinds-animal, vegetable and mineral-in various degrees, depending upon local circumstances; but the dangers arising from absorption by water of such salts and minerals as render it unfit for domestic purposes are not so serious as those derivable from the organized growths that abound in water tainted with decomposing vegetable or animal matter. All surface waters contain micro-organisms that subsist upon dissolved or suspended substances, although the quality of a water exercises a powerful influence upon the growth and predominance of particular species among those that inhabit it; and it is worth noting that water which has percolated to some considerable depth, while it may be chemically impure, is often practically free from bacteria, unless it is mixed and contaminated by surface water reaching it direct through fissures, and that, too, even when the surface soil is highly charged with them. But we are not concerned at present in dealing with waters obtained from deep wells. A fertile source of pollution arises from the manuring of land with artificial manures, such as putrid fish and guano, which are more to be feared even than any natural manures; and it is doubtful whether any danger is to be apprehended from cattle grazing on the watersheds, for it is not yet conclusive that certain diseases common to cattle are communicable to man.

Without question, however, the pollution which is most dangerous to man is that produced by himself. The untreated excreta of the human being is always a source of danger, but when it proceeds from a diseased human being it carries with it germs which may easily be communicated to others, and produces disastrous results. Hence the danger arising from the presence of human dwellings on the areas from which our water supplies are obtained, especially if they are situated in the immediate neighborhood of the streams or intakes; for while it is true that a distinct increase in the number of organisms is invariably to be found in the proximity of human habitations, the real danger is not due so much to the increased number (all of which may be harmless)

as to the proportionate increase of the probability of the presence of such as may be pathogenic and prejudicial. Many cases of serious outbreaks of typhoid, cholera and other diseases have been clearly traced to such sources of pollution; especially is this danger aggravated if the water is drawn direct into the mains from the stream or feeder at a point immediately below human dwellings, or from small reservoirs; for it is well known that large storage reservoirs not only facilitate sedimentation in the removal of suspended solids and mineral matter in solution, but also effect a very considerable bacterial improvement, especially if flood waters, containing large quantities of decaying vegetable matter, such as leaves and peat, are excluded; and although it is generally believed that running water, after a few miles of flow, will purify itself a high degree, the amount of purification that takes place naturally, such as by oxidization by air and light, is comparatively limited, so far as the disappearance of disease germs is concerned. Their dispersion through the mass of the water and the greater dilution caused by the increasing volume of flow, are probably the greatest factors in the apparent lessening of pollution; and in this country-especially in Lancashire-the streams, except where the topographical conditions are not favorable for the development of large industries, almost invariably receive such quantities of trade refuse and effluents as to stamp them as altogether impossible sources of water supply before they have become sufficiently large to be of value as such.

There are other sources of pollution which I need not allude to, because for the most part they may be controlled and eliminated. by the agency of those in direct charge of water undertakings; but, having pointed out some of the principal sources and the liability of our water supplies to contamination, and the possibilities arising from such, the question now presents itself for consideration: How may we protect or safeguard them?

At present the law does not give sufficient protection. Since 1847 there has been no general legislation for the protection of the gathering grounds of waterworks, as distinguished from other watersheds, and while the Rivers Pollution Act, 1876, applies to all rivers and watercourses, it does not contain any special enactments with reference to rivers and streams on which we are dependent for our water supplies; and it might with advantage be made more stringent and effective in preventing the fouling of water intended for domestic purposes, by enforcing penalties in cases of pollution and the supply of unwholesome water.

Some other method of protection must, therefore, be adopted meantime, and it is interesting to notice the different steps taken by water authorities in this country, and also abroad, to attain this end. Germany depends upon filtration alone, and has spent millions in purifying turbid and polluted river waters; France and Austria have striven for mountain spring waters, and have built hundreds of miles of costly aqueducts to secure them; and in the United States, where the importance of protecting the gathering grounds is widely recognized, more favor is shown to making regulations and legal enactments for their protection than in owning them, and in several of the States very stringent measures have been adopted and are imposed. In this country, however, recent efforts have been directed to the purchase of the watersheds, thus securing their complete control and management entirely in the interests of the water consumer, which is certainly much more effective than protecting them by legal enactments.

Manchester was among the first authorities which acquired powers for purchasing the watersheds, although I claim for Bury the distinction of being the first to carry into effect the objects aimed at in thus securing complete control over them; and no doubt the experience gained by the Manchester Corporation in the Longendale Valley induced them to buy up the whole of the watershed draining to Thirlmere, extending to 11,000 acres. The corporation have since been amply justified in their action, more especially as the water is laid on direct from the lake to the consumers. Liverpool possesses the power to acquire the Rivington, as well as the whole of the Vyrnwy, watershed, the latter extending to 22,000 acres, notwithstanding that provision is being made for the whole of the water to be filtered. Birmingham has similar powers over the watersheds of its new supply from the rivers Elan and Claerwen, in Mid-Wales, reaching to 45,000 acres, of which 40,000 consist of open mountain pasture and moorland, carrying not more than one sheep per acre. Glasgow has adopted a different course, by entering into an arrangement with the landowners not to lease land for building purposes around Loch Katrine, nor within a drainage area extending to 20,000 acres; while Edinburgh, although it has a very complete system of filtration, and obtains its water from moorland very sparsely inhabited, protects its watersheds by contracts with the proprietors of the land and by legal enactments.

Other places might be enumerated which have adopted this precautionary measure, but there are many more which depend