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ingress of rats from the streets and upper floor levels. In the City, unfortunately, it
is only the more modern buildings which are so satisfactorily constructed, the older
buildings present all degrees of deviation from this ideal ; in fact some would appear
to have been constructed with the object of not only conducting business, but of
furnishing rats with a maximum of convenience.
(7) RAT-PROOFING.—The principles to be observed in rat-proofing existing
buildings are the following :—
(i.) A good cement floor should be laid down, particularly in the basement.
(ii.) All holes in basement walls should be filled up with brick or glass and cement.
Loosely filled spaces should similarly be treated, particularly where drains run in close
proximity to the floor.
(iii.) In old buildings where lath and plaster ceilings are attached to the joists or
rafters, the lath and plaster should be removed leaving the joists exposed so that no tats can
harbour there. In new buildings floors and ceilings are usually of solid construction.
(iv.) Doors should be made to fit satisfactorily and, if necessary, the foot should be
fitted with sheet iron.
(v.) Openings into basements such as area windows, or the ventilating windows
of W.C's near the ground level, should be fitted with small mesh galvanised iron wire
netting—1/2-inch mesh is a suitable size.
(vi.) Disused drains which formerly opened into the basement or other parts of the
premises should be removed and the opening at the sewer end satisfactorily made tight
with cement.
(vii.) A sound sewer is also necessary as a security against infestation of buildings
since the rats leaving the sewer will burrow along the side of drains and reach the basement
if any weak point can be discovered.
(viii.) Walls should be impervious to attacks by rats from outside.
(ix.) It seems almost necessary, in view of the possibility of the black rat gaining
access to upper floors, and particularly where these are used as restaurant kitchens, to
guard the posts and carriers of telegraph wires, and in other ways to construct suitable
roof defences.
(8) FOOD SUPPLY.—In addition to rat-proofing, every precaution should be
made to ensure that food is kept in rat-proof receptacles or chambers, and in places
where meals are consumed on premises even the crumbs should be removed each
evening. In addition, refuse which is stored in kitchens should be contained in metal
tins and the covers should be invariably tight-fitting and kept in position.
Since writing this Report I have noted the following observations by
Dr. Louis Sambon, delivered in the course of a lecture on Tropical and Sub-tropical
Diseases before the Royal Colonial Institute, and reported in the "Lancet" of
February 28th, 1920
"The slaughter only renders conditions more favourable for the multiplication of the
"survivors. The increased mortality is met by increased birth-rate, and, as everyone knows,
"the rat's breeding powers are incredible. Five to 10 litters in a year, 6 to 20 young in a
"litter, and the young able to breed in less than three months ! Besides, what would be the
"use of destroying rats unless we made adequate provision to prevent more rats from
"landing ? Every ship brings rats, especially grain ships, a thousand and even 1,700 rat
"carcases have been counted after fumigation of a single ship, and thousands of ships reach
"our ports. What we can and should do is to render our wharves, quays, markets, store"houses,
and other public buildings rat-proof. The rat must be entirely excluded from
"occupied buildings. He must be de-domesticated, if I may use the expression, he must be
"built out of existence—as Surgeon-General Blue tersely puts it. Attracted by food and
"cover, he has overcome every fear of man and imposed himself upon us as an effronted and
"dangerous commensal. The proper storage of food, the immediate removal and burning
"of all food wastes, garbage, and rubbish, the destruction of places in which he may find
"harbourage, and the contrivance of architectural modifications apt to cut off his approach,
"the liberal use of concrete, wire netting, and sheet metal will certainly discourage him."