A portable frame, containing steps for the feet. There are various kinds, most of which are too familiar to the readers of this work to need description; but there is one of a very ingenious description, described under the head of Fire Escapes, invented by Mr. Gregory, which is evidently applicable to a great variety of purposes, wherein common ladders are useless, or of difficult employment. Ladders are very advantageously employed in the raising of weights, by the addition of a pulley-wheel at the top, or suspended over them; passing over this pulley is a rope, to one end of which is attached the article to be raised, (a tea-chest, for instance, out of the hold of a ship;) a man then ascends the ladder to the required height, and steps on to a foot - board, properly contrived for the purpose, which is attached to the other end of the rope just mentioned; the man's weight, then, more than counterpoising the tea-chest, he rapidly descends, while the chest ascends through the same space. In this manner the tea is unloaded from the East India Company's dock at Blackwall, and it is very probable there is not a more efficient mode of applying a man's labour for that purpose, and the mechanism is cheap, convenient, and easily adjustable to the space.
The man has only to ascend the steps of the ladder, and he is refreshed in the descent, the frame in which he stands sliding over the inclined plane of the ladder.
Mr. W. Hilton has likewise ingeniously converted the fixed ladder against a trap door, into a crane for lowering heavy or bulky articles, such as a pipe of wine from a warehouse into a cellar, for the communication of which invention to the Society of Arts Mr. Hilton was rewarded by an honorary medal.
A very convenient folding ladder is manufactured by Mr. Green, of Goswell-street, of which the cut in the preceding page is a representation. Fig. 3 shows the ladder as opened out for use; Fig. 2 shows the ladder in section, half open, and the manner in which the rounds are jointed to the side rails; and Fig. 1 exhibits the ladder folded up close, forming exteriorly a round pole, tapered at each end. Mr. Green has likewise contrived an excellent ladder for the purpose of rescuing persons who may have the misfortune to sink under ice.