66 REPORT — 1851. 



On the Air and Water of Towns. Action of Porous Strata, Water and 

 Organic Matter. By Dr. Robert Angus Smith, Manchester. 



It is becoming daily more important to find out from what source it is best 

 to obtain water for great towns, and by what means it is to be collected. It 

 is probably true that a mode of supply suited to the conditions of all parts of 

 the country is not to be our direct aim, as every town must have its supply 

 modified by its own peculiarities of position, but it has still to be settled what 

 water is preferable when there is a choice before us. I have here put together 

 a few facts and reasonings which seem to me to deserve prominence, and 

 which have not, as far as I know, been sufficiently' dwelt on. 



Water has been got from rivers and small streams, sometimes from the 

 surface drainage of ground, and from deep wells and springs. The use of 

 well-water is the first that is resorted to where there is no stream or spring, 

 and where the inhabitants are not too many to be satisfied with such a source. 

 The water from this mode of supply is often exceedingly pure and brilliant, 

 according to the nature of the filtering-bed; but as most soils have a good 

 filtering-bed underneath, want of cleanness is not a common fault of wells. 

 There is in fact a proverbial purity about springs and wells ; and mountain 

 streams frequently share in receiving the same character from, the literary and 

 poetic observers of nature. It is interesting to know how this purity is attained. 

 There are many springs which never become muddy, which possess a con- 

 stant brilliancy, which never become cool in winter and never warm in sum- 

 mer. They seem to be unaSected by what is going on at the surface of the 

 ground. From this it appears that there is a purifying heat-regulating 

 action going on beneath. The surface-water from the same place, even if 

 filtered so as to become clear, has not the same purity, i. e. the same freedom 

 from organic matter or the same brilliancy ; neither has it the same amount 

 of carbonic acid or the same quantity of oxygen in it. There are influences 

 therefore at work, under ground, which are not at work on the surface. 



The rain which falls has not the same purity, although it comes directly from 

 the clouds ; it may even be wanting in cleanness, as is often the case ; it may 

 be nauseous to the taste, and be wanting in carbonic acid and in oxygen. It 

 never has the brilliancy of the spring water, nor is it so free from organic 

 matter. For these reasons all the world has admired spring water. The 

 mountain streams have had their share of admiration, and sometimes they 

 equal the spring water. Spring water and well water are of course essen- 

 tially the same ; both have passed through a considerable depth of soil. The 

 well has been dug in order to convert a portion of the surrounding ground 

 into a filter, and" in order to make a depositing place for the water which 

 trickles through. The spring has made its way through similar passages, 

 sometimes easily traced, and has the advantage of coming to the surface clear, 

 without any such accidents as may occur to disturb the purity of a well. In 

 many parts of the country these springs are hard ; they often go through a 

 great extent of soil and collect a considerable amount of inorganic salts, 

 varying, from the strong solutions found at celebrated watering-places, to the 

 milder form of a few degrees of hardness. Whilst the inorganic matter in- 

 creases with the depth of the flow of water, the organic matter decreases, and 

 may be said entirely to disappear. This is accomplished even at a depth not 

 very great. It always happens, except when the well is not sufficiently 

 sheltered from the surface-water, either from the soil being too porous in 

 proportion to the depth, or from the surface-water having in some way a too 

 readv passage into the well. 



In" examining this matter, I have been struck with the numerous cases 



