68 DR. R. ANGUS SMITH ON THE EXAMINATION 



We see the influence of the coast also as we go on towards 

 Liverpool, and between the Isle of Man and Lancashire. 



"I consider that O'ooooi per cent, oxygen by weight, 

 or 0*7 grain per lOO gallons, marked the limits of the 

 Glasgow sewage. If the sewage were not all expended, 

 the amount would be greater, because the lochs and their 

 streams do not show a higher number. Whenever the 

 water of the Firth falls down to that of the streams, we are, 

 as I suppose, receiving the air at least as pure as the air 

 above the streams on the hills, and may be contented. 



'^ Some people will perhaps demand more than this 

 number. I have not made examinations far enough 

 towards the ocean to enable me to speak of it; but it 

 seems to me that the numbers O'oooor per cent, by weight, 

 or 0*7 grain per lOO gallons, of the streams, and 0*00005 

 or 0"35 grain per 100 gallons, mark two very import- 

 ant points. The first characterizes air which is certainly 

 most wholesome and agreeable ; the second is that ocean - 

 air which some persons require, but which to others is said 

 to be too strong. On the meaning of this expression 

 ^^ too strong,'^ I will not attempt to speak ; but it is very 

 much used by a great public, and it must have a wide 

 foundation. It is apparently certain that to some it is 

 important not to have the extremely strong or perhaps 

 purest air. 



"These observations seem most curiously to coincide 

 with general observation. The current of the Clyde keeps 

 to the south ; and we see that the water changes less rapidly 

 there. At the north the direct current is not much ob- 

 served, and the influence of the lochs on fiords is seen. 

 The water from them presses against the Clyde current, 

 and aids in keeping it to the south-east. This had in- 

 fluenced the building of the numerous residences on the 

 Argyle side, lining all the coast. The population had 

 not found it needful to make a chemical analysis, but had 

 seen where the purest water was with the unaided eye. 

 A mode of observation, apparently quite as good as chemical 

 analysis, is the examination of the rocks on the coast, the 



