54 
which have a great utility in the economy of the universe, 
and whose subordinate action may even he absolutely 
necessary for the existence of higher forms of life, such 
evolution has not yet been experimentally proved. Con- 
versely, however, we have, meanwhile, definite evidence 
that fresh air and sunlight attenuate the virulence of 
pathogenic microbia. Even this partial knowledge is of 
great practical importance. It cannot be overlooked that 
vitiated air and darkness generally go together, and that on 
the other hand fresh-air and sun-light are usually co- 
existent. Both the first-named conditions are necessarily 
associated in the covered sewer. Whether the covered 
sewer does or does not actually evolve the disease is at 
present a matter of speculation; but that the peculiar 
conditions of the covered sewer nurture and strengthen the 
disease may be regarded as experimentally proved. Now 
I find that in connection with the Ship Canal project it is 
proposed to construct a covered sewer to receive all the 
sewage of this city. Of the conditions to be provided in 
this culvert we have as yet only the vaguest intimations. 
I confess that I, for one, look forward with the greatest 
anxiety to the prospect of such a huge drain, in which so 
vast a mass of organic matter will be allowed to putrefy in 
darkness and in the midst of an environment of foul gases. 
It seems to me that this Society will only be true to the 
traditions of its earl}^ history, and discharge a duty to the 
city to which it pertains, by watching this culvert scheme 
closely, and asking what provision is to be made for con- 
tinuing the hygienic influences at present exercised on the 
Irwell by free oxygen and sun-light (so far as we possess 
either one or the other in this district), or what precautions 
are to be taken to counteract the vicious consequences of 
the absence of both ? 
The philosopher sees the same principles throughout 
nature ; he learns to recognize that simplicily and harmony 
