In some refineries the travelling cranes are now run by electricity, which still further facilitates the work.
Operating in a current of carbon dioxide facilitates the process by preventing overheating.
The tuft of hairs at the base facilitates rapid dispersion of the seed, early germination of which is rendered desirable owing to its tenuity.
As each stage is worked out, the floor level is connected with that next below it by means of an incline, which facilitates the introduction of the packing material.
The addition of a foot-bridge greatly facilitates the raising and lowering of these shutter weirs, and also aids the regulation of the discharge; but it renders this form of weir much more costly than the ordinary frame weir, and where large quantities of drift come down with sudden floods, the frames of the bridge are liable to be carried away, and therefore boats must be relied on for working the weir.