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"Pipes.—In passenger vessels the mass of pipes running overhead along alleyways forms not only
a convenient rat-run, but also a nesting place. If the pipes are spaced out this is avoided, otherwise screening
may be necessary.
"Casings for Electric Cables, Signal Wires and Telegraph Wires, &c., should be of metal, and
closed at ends, or should be of some open type construction.
"Fire Boxes, Switchboard Boxes, &c., frequently provide harbourage with communications along
pipes, &c. These should be of metal construction or at least be flashed with metal wherever gnawing is
possible and where pipes or cables enter them.
"Deck Lockers for Life Belts, &c., should be of metal in preference to wood, and be set directly on
the deck or on a solid base, or with a clear space of at least ten inches underneath. If of wood the bottom
and edges, where gnawing is possible, should be flashed with sheet metal.
"These are the principal items requiring attention in the rat-proofing of ships under construction.
Though they set a standard to which we should endeavour to approach as nearly as possible, we shall
usually have to be satisfied with much less in ships already in commission, and I will therefore indicate what
we may reasonably hope to achieve in the latter.
"Ships in Commission.—All wooden floorings and limber boards should be examined, and such as are
broken or defective should be repaired or replaced.
"Ceilings in holds, unless tightly butted, should be flashed at edges and around pillars, frames, pipes, &c.
"The space between wooden ceilings and tank tops should, if sufficiently deep to afford rat-harbourage,
be screened from the bilges at the margin plates as already described for, as has recently been shown in
experiments carried out by the Ministry of Health with the assistance of the Imperial College of Science and
Technology, neither hydrogen cyanide nor sulphur dioxide can get into this space in measurable amounts
during an ordinary fumigation.
"The cement filling between frames at ship's side must be kept in good repair.
"Box type wooden casings over pipes, &c., should be replaced by one of the open type casings described.
If this cannot be done the wooden casings must be kept in good repair and be flashed with sheet metal
six inches wide at top and bottom. If such casings do not extend from the ceiling or deck to the deckhead
the ends must be closed with sheet metal flashing.
"Metal flanges or collars should be fitted where pipes pass through decks or bulkheads if there is room
for a rat to get through.
"Doors, particularly in store rooms and galleys, must be made rat-tight, and the bottoms and the
thresholds be flashed with metal if exposed to gnawing.
"Careful attention should be paid to the sheathing over insulation.
"Lockers, bins, cupboards, &c., should be replaced by metal structures if they are in bad condition.
In any case they must be kept in good repair, and be flashed where exposed to gnawing. Bat-harbourage
above and below must be eliminated or protected.
"Boxed seats and settees should at least be fitted with lids or covers. The interior should be sheathed
with metal if there is a hollow wall or floor construction behind or below. Metal collars should be fitted
round the openings for any pipes running through the enclosed spaces.
"Forepeaks and afterpeaks should be treated as far as possible on the lines previously indicated.
"Broken or defective or badly fitting hatch covers must be repaired or replaced.
"All wooden partitions must be kept in good repair and flashed with metal where pipes, beams, &c.,
pass through. Hollow partitions must be flashed on both sides at edges if exposed to gnawing.
"Openings between partitions and the deck or deckhead should be closed with wire mesh or perforated
sheet metal.
"Finally, all refuse which might be food for rats should be cleared up promptly and put in rat-proof
bins until it can be finally disposed of. It is desirable that the crew should have messrooms with metal food
lockers, and that no food should be consumed or stored in their sleeping quarters. It is remarkable how
many rats can be fed on scraps of food left on floors, tables, &c., overnight, and how much can be done to
reduce the number of rats by cleanliness and tidiness.
"I agree with Mr. Holsendorf that the correction of rat-harbourage should be indicated on certificates
by the words 'eliminated' or 'protected' as the case may be. When harbourage has been eliminated
it appears to me that in subsequent certificates the word 'none' must appear in the rat-harbourage
column. But I agree that harbourage which is only protected should continue to appear on certificates with
the word 'protected' in the 'corrected' column, provided the protection is in good repair and efficient,
because it may break down at any time. Mr. Holsendorf suggests that we should record 'protected'
harbourage as 'inactive.' If we use this word at all we should use it also in regard to uncorrected ratharbourage
which is not being used by rats'at the time of inspection. The word 'temporary' in regard to
harbourage seems to me unsatisfactory, and personally I think the best plan is to indicate briefly
on certificates the nature of the harbourage, because in this way ship's officers and others will learn what the
defects are, and will be the more likely to take an interest in rat-proofing. A great deal can be and is
already being done by ship's carpenters under the direction of ship's officers. Such entries can be made on
the large forms of certificates we use, but, unfortunately, on the single sheets used by other countries the
space is too limited.