190 Sewage and Sewerage. [April, 
Engineers, vol. xxiv. Session 1864-1865), and also in Dr. Parkes’s. 
‘Practical Hygiene, p. 306, and we pass per saltwm, therefore, 
from the consideration of sewage at its source and in its place of 
production, to the consideration of its ultimate disposal and destina- 
tion, remarking, in so passing, that sewers and main drains need 
ventilation as much as sink pipes and house drains; and that though 
tall chimneys, such as those of furnaces and factories as now 
employed at Woolwich, or other tall vertical tubes, as recently, at 
Malta, may help in doing this, it is better to reduce the need for it 
within the narrowest limits, by securing that rapid and constant flow 
of water through the sewers which will prevent the generation of 
foul gases within them. 
Entering now upon the debateable ground of the disposal of 
sewage, we shall keep before our eyes the aphorism, “ C7tvws emergit 
veritas ex errore quam ex confusione ;” and feeling ourselves that 
the dogmatism of one man calls forth the research of another, and 
so is ultimately profitable to both of them and to others, we beg, at 
the same time, our readers to consider that if we make categorical 
statements, we do not impose them as articles of faith, to be 
required of any man to be believed, but propound them merely 
and shortly as results to which investigation of the subject has 
brought us, and may bring them or may not. As it seems to us, 
then, upon the evidence before us, any town-corporation which 
could command an acre or so of the lightest and poorest land for the 
reception in open grips and by gravitation of the sewage of from 
every fifty to every hundred of its inhabitants, might safely count 
upon a handsome return, in reduction of their local rates, from the 
sale of the grass crops they would thus and there raise. But it 
appears that all these conditions must be present if a pecuniary 
profit is to be secured, besides and beyond the great negative 
saving which all such disposal of sewage effects, in the way of 
prevention of disease. When guano has become scarcer, and the 
farmer more enlightened, it will be otherwise; but, in the mean- 
while, it is easy to see that, in many cases, no adequate supply of 
land may be cheaply available, or that such as may be so, and may 
also have the sandy or loamy constitution which fits it for irrigatory 
urposes, may yet be situated so as to stand in need of an expensive 
ifting and pumping apparatus; or, finally, that the only available 
area may be an impermeable clay, and thus be physically unfit for 
the duties which its chemical character would excellently qualify 
it for. The observation of the great comparative purity of the 
water which flows out of the thick felt which the American 
weed forms now in so many of our ditches and sluggish streams, 
has suggested to us that, in such unfortunate cases as those we 
have just specified, arrangements might be made for sending the 
sewage of towns through a network of ditches filled with this 
a 
