Of cleaning a Ship's Hold.

THE practice of allowing filth to accumulate in a ship's hold to a great extent before it is cleaned out, is another link in the morbid chain of humidity, by which the inmates of the lower deck are often doomed to suffer.

No rule can be laid down for cleaning a ship's hold so good, as that it must be done as often as it becomes filthy; and it follows, as a consequence, that those ships, which are most famed for having their lower decks washed, soonest acquire an accumulation of filth in their holds.

In tropical climates, we are most imperatively called upon to be punctual in this respect, in order to prevent fever being generated by such

a cause.

Again, in colder regions, such punctuality is not necessary, as cold has the power of partially arresting the process of decomposition. I am here compelled to observe, that cleaning a ship's hold is a duty that is in general carelessly performed, because it is an unpleasant part of the service, and one that leaves no external mark for approbation, like washing and scrubbing. Hence, it is usually neglected or

evaded, by saying there is no necessity, until fever has commenced its ravages.

Cleaning a ship's hold, however, is genuine cleanliness, and as salutary as washing the body and putting on dry clean linen; while washing decks may be compared to shifting oneself into wet clean clothes. It will appear rather paradoxical to assert, that an extraordinary ship for washing is always a dirty one; but when we recollect the general tendency of the operation is that of washing filth from the surface of the lower deck into the holds, through the medium of the scuttle holes, &c. the observation then becomes less objectionable.

Of Bilge Water.

WATER is never obtained quite pure from Nature, for even rain water is known to contain small traces of the muriatic and nitric acids:

and, in watering a ship from spring water, it is always found to hold a certain quantity of earthy salts in solution.

When river or marsh water is used, they are constantly found impregnated with animal and vegetable exuviæ in a suspended state, undergoing decomposition. On going to sea, after being so watered, the heat and impure air of the holds,

together with the motion of the vessel, soon produce a spontaneous change in the water in cask, and that oozing through the ship's sides, and these united agencies give origin to that fetid smell, commonly said to arise from the "Bilge Water." This is, in fact, a mixture of impure sulphuretted and carburetted hydrogen gases, varying in strength, in proportion to the quantity of foreign matter contained in the water, newness and tightness of the ship and casks, and degree of heat and motion at the time.*

Both these gases are highly deleterious to animal life, and, from their being of greater specific gravity than atmospheric air, they will not give up their residence in the lower department of a ship, (where they were generated,) unless dislodged in the way hereafter to be mentioned in the chapter on Dry Rot.

*Carburetted and sulphuretted hydrogen gases are formed in the following way:-When water is partially decomposed, either by being kept long in cask, or subjected to great heat and pressure in oozing through a ship's sides, the carbon of the wood unites with the hydrogen of the water, to form an impure carburetted hydrogen gas. During hot weather, and when there is great motion in a ship at sea, this gas may be collected in the well of a ship's hold, by a bottle, after the same manner that gases are collected in a pneumatic trough. Sulphuretted hydrogen gas is formed thus: during the putrefaction of the animal and vegetable matter contained in water, sulphur is evolved, in union with hydrogen, to form this fetid gas.

6

Of wet Hempen Cables.

THE common practice of coiling down wet hem. pen cables in the tier, immediately after they have been hove in, fully saturated with moisture, is another very injurious and unskilful custom in the royal navy. First, by conveying moisture into the tier, from which a continual evaporation is kept up; and, thus, the inmates of the lower deck are not only doomed to suffer, by internal, but from all circumambient causes. 2dly. Every one who is only acquainted with the rudiments of science, must be fully aware, how much the destruction of a cable is promoted by adding moisture to the heat of the tier (the chief agents of decomposition,) on a perishable article like a hempen cable.

Farther, humidity, like caloric, has a tendency to equilibrium: hence, the hammocks, men's clothes, and every article on the lower deck absorb moisture, until they reach an equal state in point of saturation with the mean of the surrounding objects.

Should a due regard for health not be sufficient to deter us from this unsalutary practice, surely, the great expence the country is put to

on that account, and the yet more important consideration of greater personal safety, ought to induce us to abandon this custom.

Moreover, when we consider that, in many perilous situations, a cable is the only connecting link between life and death to a ship's crew, one would not, a priori, anticipate any objections to preserving it in as perfect a state as possible. I would, therefore, recommend, that cables should uniformly be allowed to dry on the main deck, (except in cases where it is necessary to have it clear for action,) before being coiled down in the tier.

The iron cable, from its uniformity in point of strength, and its non-absorbing qualities, possesses advantages over the perishable hempen one, both in regard to safety and salubrity, which ought not to be forgotten in comparing them.