The great point is to allow no possibility of the cargo or ballast shifting position even in the most violent rollings of the vessel.

With this end, great attention must be paid, not only to the bulk taken in, but to the nature of the bulk, and whether there be a full or only a partial cargo.
In most kinds of freight the stowage is accomplished by means of a screw.

Thus, in a load of tobacco or flour, the whole is screwed so tightly into the hold of the vessel that the barrels or hogsheads, upon discharging, are found to be completely flattened, and take some time to regain their original shape.

This screwing, however, is resorted to principally with a view of obtaining more room in the hold; for in a full load of any such commodities as flour or tobacco, there can be no danger of any shifting whatever, at least none from which inconvenience can result.

There have been instances, indeed, where this method of screwing has resulted in the most lamentable consequences, arising from a cause altogether distinct from the danger attendant upon a shifting of cargo.