Army sanitation : a course of lectures delivered at the school of military engineering, Chatham / by Sir Douglas Galton.

  • Galton, Douglas (Douglas Strutt), Sir, 1822-1899.
Date:
1887
    except possibly in a case where the ground is so elevated and porous as to ensure that water never remains in it; and if there is higher ground adjacent, the water from the higher ground should be carefully cut off by underground catchwater drains, and led away from the vicinity of the site. It is no doubt impossible always to procure a perfect site for building, but it will be necessary in the construction of buildings upon a given site to discount any departure from these qualifica- tions by additional sanitary precautions in the building—i.e. by increased expenditure. To test the healthiness of a site, an inquiry into the rate of sickness and mortality in the district will afford valuable infor- mation. But care should be taken not to be guided by the mortality alone. The nature of the diseases, and the facility, or otherwise, with which convalescences and recoveries take place, must also be taken into account. I have now exhausted the time at my disposal by the explana- tion of certain preliminary questions which it is necessary that you should consider when you are called upon to provide for the location of a body of troops in a healthy locality. A skilled sanitary officer will be a man of many expedients, derived from close and intelligent observation, and in his works he will strive to save labour. Every country has its character impressed on its surface contours, and these the geologist and engineer will read at a glance. Wide and flat areas will indicate, as a rule, a soft subsoil; a steep gradient will indicate a subsoil of some hard material, such as gravel; rock will generally show above the surface ; where there are mountains, there will usually be at the base mounds of material —particles weathered from the rock and admirably suited for road-forming. This was the case in the Crimea on the margin of the road from Balaclava to the front. In the lower part of the valley this road, during the first winter, was worn into almost impassable mud by the wheel traffic. To repair this road the Boyal Engineers were blasting rock at a distance to break into road material, when at the foot of the mountain, and close to the road, there were thousands of tons of stone ready broken- that is, the ' talus' weathered and washed down during untold years from the mountain. If this material had been used from the first to maintain the road to the front in proper order, there need have been no railway; much suffering would have been prevented, and many lives would have been saved. This rapid resume is only sufficient to suggest to you points for observation. The selection of a healthy site for a camp or a barrack will depend upon your own power of applying the sanitary knowledge you have acquired to the particular case. I trust that the remarks I have made to-day will impress upon you the extent of the field of knowledge which this branch of your profession alone requires you to traverse.
    LECTUEE II. PURE AIR. In my first lecture I endeavoured to explain to you the general principles which should govern the selection of a site for a camp or for permanent buildings, were conditions of health alone to be considered. If for military reasons it has been necessary to take a site which presents unsatisfactory sanitary conditions, then the arrangements adopted in "the construction of the buildings must be such as to discount the unsatisfactory features and reduce their effect to a minimum. The conditions which you have to secure are summed up in the words—pure air and pure water, and to secure these the principal consideration is the speedy removal of all refuse matter. Causes of Impurity in Air. What are the conditions which regulate the purity of the outer air ? 1st. There are causes at work owing to the existence of plants, animals, and men, by which the surrounding air is being constantly filled with impurities ; and 2nd. Nature has provided means by which the purity of the air is being continually renewed. Every analysis of air shows the presence in varying propor- tions of carbonic acid, vapour of water, organic matter, ammonia, suspended matter. Organic Matter. Organic matter and gases from decaying vegetation are con- stantly passing into the air, but the various processes connected with life, and especially human life, and occupation, are among the most fertile causes of the pollution of air in the vicinity of habitations. The quantity of organic matter in outside air varies considerably, within certain limits, from day to day and from hour to hour on the same day. It is least in fine weather, it increases in dull weather, it is greatest in fogs. It is washed out of the air by means of rain. Dr. Eussell's experiments in London show that city air contains twice as much impurity as suburban air, but that the
    impurities are the same in character, and that in country air the impurities were much less ; and on Dartmoor the air was uncontaminated either by the products of combustion or by the decomposition of animal or vegetable substances. Let us now consider how we affect the purity of air by our presence in a room. What takes place is as follows:—Putrefying organic matter is thrown off from the human body in the process of breathing and transpiring :— 1. The oxygen is diminished. 2. The carbonic acid is increased. 8. A large amount of watery vapour is produced. 4. There is an evolution of ammonia and organic matter. 5. A considerable amount of suspended matter is set free, consisting of epithelium, and molecular and cellular matter, in a more or less active condition of putrefaction. At the same time, portions of epithelium are constantly being given off from the skin, and even pus cells from suppurating surfaces—as, for instance, with surgical cases in hospitals. Putrefaction. Putrefaction is the process which nature employs to make the matter which has formed part of an organic structure again available for the support of life. And as the investigation into the action of ferments or putrefaction has an important bearing upon practical hygiene, it is desirable that I should briefly allude to the present state of the theories on this subject. Animals or vegetables, whilst they are in the condition which we call alive, are continually employed in working up into the solid matter of which their bodies are composed, gases taken from the atmosphere, or nitrogenous and saline substances which are dissolved in water. For instance, if you take some seeds of mustard and cress, and put them on a piece of flannel in a plate with water, and place the plate in the sunlight near your window, you will soon have a luxuriant crop of mustard and cress, derived from a combination of the salts dissolved in the water and the gases in the air, assisted by the sunlight. Thus it is possible, by means of air, and the gaseous elements it contains— by means of water, and the elements contained in rain—to create and develop the smallest blade of grass as well as the largest oak. An oak, a blade of grass, an animal that lives by eating grass —as, for instance, a sheep—or a carnivorous animal that lives by eating the sheep—as, for instance, a lion—or, indeed, each one of you here present, were all originally water, carbonic acid, salts of ammonia, and soluble mineral substances. But when once these substances have been converted into the oak or the blade of grass, or into the sheep, or the lion, or the man—that is to say, into organic matter which can be handled, this new matter is as it were paralysed, and incapable of contributing to the nourishment of a new vegetable life ; and if it were to remain
    perpetually in this state—if its elements were never to pass back into the atmosphere, or into the water which circulates around the globe—the atmosphere would soon be deprived of the elements it contains, out of which organisms are produced; water would be deprived of its nutritious matter, and life would become impossible on the surface of the globe. As a means of enabling life to go on continuously in the world, nature has provided minute microscopic beings, which we are barely beginning to know, but which have always existed side by side with us in the larger world of animals and plants with which we have always been familiar, which, at the moment when life has ceased in a plant or an animal, begin to redistribute its component parts back into the air and the water. Putrefaction, whilst it is one of the purifying agencies of nature, produces vapours or gases injurious to health, which, however, are counteracted by thorough oxidation; and when organic matter is thrown off from the body a current of air may either carry it away, oxidising or burning it up, as it were. Ammonia. Ammonia is present wherever there is organic matter. It comes from all living organisms, and is equally necessary to build them up. It is therefore present wherever plants or animals grow or decay. As it is volatile, some of it is launched into the air on its escape from combination, and it is always found in the air. As it is soluble in water, it is found wherever we find water on the surface of the earth, or in the air, and probably in all natural waters, even the deepest and most purified. As a part of the atmosphere, it touches all substances, and can be found on many; it is in reality universally on the surface of the earth in the presence of men and animals, attached more or less to the surface of all objects, but especially to all found within human habitations, and the habitations of all animals. Thus a room that has a smell indicating recent residence will, in a certain time, have its objects covered with organic matter, and this will be indicated by ammonia on the surface of objects. Hence ammonia, being more readily observed than organic matter itself, may be taken as a test, and the amount will be a measure of the impurity. It is probable that the chief cause of the presence of ammonia on surfaces in houses and near habitations is the direct decom- position of organic matter on the spot. In towns the air is filled with the impurities which it is the practice to retain in and about the houses, on the street surfaces, and on open spaces within and around the city area. The whole subsoil of our cities used to be perforated with cesspits, which were generally porous, and were preferred to be so, because it rendered frequent emptyings unnecessary. The subsoil of all large Indian cities has been saturated with the filth of generations, just as the subsoil of large cities in
    ancient times had been saturated. From this saturation these ancient cities became foci of disease, and were abandoned. Oxygen. The air of mountains and great plains contains more oxygen than that of cities, where the air is being breathed, and where putrefaction may be supposed to exist. Dr. Angus Smith has found that a diminution of oxygen and an increase of carbonic acid is decidedly apparent in crowded rooms, theatres, cowhouses, and stables, and near middens, in Manchester. The diminution is no doubt small. The average quantity of oxygen in pure air amounts to 21 parts out of 100. In impure places, such for instance as in a sleeping room where the windows had been shut all night, or in a lecture theatre after a lecture, or in a close stable, the oxygen has been found to be reduced to as little as 20 parts in 100. That is to say, a man breathing pure air obtains, and he requires, 2,164 grains of oxygen per hour. In bad air he would, if breathing at the same rate, get little over 2,000 grains of oxygen an hour, that is, a loss of about 8 per cent. ; and this diminished quantity of oxygen is replaced with other, and in almost all cases per- nicious matters, and although the quantity is no doubt small, it becomes appreciable from the large amount of air we inhale, viz., from 1,000 to 2,000 gallons of air daily. A current of air either carries away the organic matter with it, decomposing it and turning it into gases, or, if it were not possible for the oxygen alone to do this, it might happen that the oxygen destroys those minute forms which have been shown to be concomitant with putrefaction and decay. Moreover, besides any poisonous action which these substances may possess, if the air is loaded with impurities, the lungs get clogged, and their power of absorbing the oxygen that is present in the air is diminished. An individual breathing this impure air must, therefore, do less work ; or, if he does the same amount of work, it is at a greater expense to his system. Mr. Romanes mentioned on a recent occasion that he had found, in examining after death the lungs and air-tubes of persons who had lived in the densely-inhabited parts of London, that they were coated in many places with soot and carbon, and thus able to act much less efficiently than the lungs of people who had breathed clear air. Carbonic Acid. Carbonic acid (C02) is slightly in excess in town air; in crowded unventilated rooms and theatres the excess is very apparent, and even in the open country an appreciable variation in the quantity present has been produced by the proximity of a flock of sheep. In normal air in the open country it varies from -29 to -32 per 1,000 parts. In cities it sometimes amounts to -42 per 1,000 parts; in a long-continued fog in the city of London as