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tide can be caused to sweep it all away to sea, nothing
will remain to complain of. This does not seem to
present any peculiar difficulty; indeed the great rise
and fall of tide makes it (so it appears to me) ex-
tremely easy. Let the main sewers deliver into one
or more covered reservoirs, built of brick on the mud-
flat, and which shall be large enough to contain the
sewage of Nelson that accumulates during twelve hours.
Then twice a day, when the ebb of tide is in full
swing, let the discharge pipes of the sewage reservoir
be opened, being of such size as to empty it in a
couple of hours. As the tide will continue to run out
for some time after these two hours have expired, it
seems likely that not a part of sewage water &c.
will remain in the harbor if the reservoir is judiciously
placed for discharging its contents into the stream of
tide, and the pipes being then closed until next ebb,
no offensive matters will be found out on the flat
to dry and rot in the sun. If it be thought that the
sewage mingling with the tide water will be disagree-
able, I think a single calculation will dispel such an
apprehension. The excreta of an adult do not
amount to 10lbs per diem, but let us, to be safe of
being on the right side, assume that weight as the
waste from every inhabitant of every age. Then
5000 people will yield 50,000lbs in 24 hours, or less
than 12 tons per tide, which will be diffused among
the water, covering a great number of acres. Now,
as a single acre of water 4 feet deep weighs 400 times
as much as the 12 tons supposed; and the water that
ebbs out is deeper than 4 feet; it is plain that none
of the human senses could discover excrementitious
matters so excessively diluted as these would be. In
times of flood the reservoir would not suffice to con-
tain a twelve hours supply, but this would not signify,
as the river in flood would probably dilute the sewage
a thousand fold in the harbor, and at such times the
sea has no power.

5. For houses situated in insulated situations, and
   consequently far from a main drain, the earth-closet,
   or in the case of the working classes, the earth-box
   seems the best arrangement. I would not say that
   its use be not in the first instance compulsory, but per-
   missive, and that it be aided by some simple organisation
   on the part of the Board of Works. The Board
   might have some hundred of boxes, say five feet long,
   three feet wide, and three deep, made and supplied
   for an annual payment to each house. Once a
   fortnight the cart, in which four or six of these
   regulation boxes would exactly pack, would call to
   exchange a box of fresh earth for one that had become
   charged with excrementitious matter. People should
   also, I think, be allowed to deposit scavenger's
   material in the box, so that that expense would be
   saved to them. Doubtless market gardener's or
   farmers near town could be found who would gladly
   supply fresh earth in the return for that which had
   become fertilised, so that the only expense to the
   Board would be the system of exchange, which a
   small rate would cover.

Though impracticable at present, I think it would
be well to bear in mind as an ultimate object, to dis-
tribute the sewage water on the meadow and other
land on the plan adopted on the Craigintinny
meadows near Edinburgh, or Mr. Mechi's underground
piping at Tiptree Farm. The almost incredible
stimulus given to vegetation would probably recoup
the outlay, the supply of water alone being very
remunerative in irrigating land in countries liable as
Nelson is to summer droughts.

I am dear Sir,
Yours truly,
F. W. IRVINE.

C. EUNTER BROWN, ESQ.

Hardy-street, Nelson, N.Z.,
May 24, 1867.

DEAR SIR,—I beg to acknowledge the receipt of
your letter of May 18th, asking my opinion on the
present drainage of Nelson.

Your letter appears to me to contain two ques-
tions, and I will endeavor to reply to them sepa-
rately.

1st. Is the health of Nelson injuriously affected by
the present sewers, as now used?

No; for I do not think that the present sewer in
Trafalgar-street can of itself do harm, as it is used
by so few houses, but if more sewers are built (as
will no doubt be the case), unless some alteration is
made regarding the place of outfall, or the disposing
of the sewage, the health of the town will be inju-
riously affected.

2. What is the best mode of drainage and sewerage
   for the future?

This is, of course, a most difficult question to
answer, and I cannot but think that the drainage
and sewerage of Nelson should not be taken alone,
but only as part of a more comprehensive scheme,
which would include the reclaiming of the mudflat.
It appears to me that it would be advisable to build
sewers in all the main streets of Nelson, and that
each house should be compelled to drain into them;
but if the sewage from those drains is to be thrown
out on the mudflat, as it is at present from the Tra-
falgar-street sewer, great mischief would accrue. To
obviate this, the sewage must either be deodorised
and utilised, or it must be carried out into the sea,
beyond, where the in-coming tide would wash it
back.

Were a sea-wall built, so as to keep the tide from
coming up beyond any given point (say in a line
from Trafalgar-street-north to the Boulderbank), the
sewage might either be conveyed to suitable tanks
made on the reclaimed land, and there properly
deodorised and made useful for manure, or it might
be emptied over the sea-wall into the tide-way, at
the ebb the tide.

The building a sea-wall would, I presume, be very
expensive; but I cannot but think that the large
amount of land that would be reclaimed by so doing
would in the end amply repay for any present outlay.
However, should this be deemed too expensive, or
not a feasible plan, it would, I think, be necessary
that the town sewage should be carried in a sewer
down the Haven road to a tank of a suitable size
built as near the Arrow Rock as convenient, and this
to be emptied during the strength of the ebb tide.

For the town, that is, Waimca-street from Bronte-
street,—Trafalgar-street north, from Trafalgar square
to Bridge-street,—Collingwood-street, from Bronte-
street to Bridge-street,—Nilo-street west and east, to
Alton-street,—Hardy-street, from Tasman-street to
Waimca-street,—and Bridge-street,—I think that a
good system of sewerage would be best, having the
more houses built, that as the town becomes larger and
more houses built, fresh sewers might be added as
necessary.

Beyond these limits a proper system of scavenging
should be established. It might be earth-closets
would prove useful, but of these I have had no ex-
perience. I believe a system of scavenging is now
carried out in the town of New Plymouth, so that
some information on this head may be obtained from
there.

I have written these few lines with a feeling of
much diffidence, for I know that I am making sug-