LIFE SPAR.

THE real value of any article of commerce depends in a measure upon the benefit which it confers upon mankind. For instance, rice, an article raised in superabundance in climates where it is an indigenous plant, bears, in all parts of the world, a price commensurate with the benefit which its consumers derive from it ;—so also with wheat, corn, &c., the prices of which vary, according to the greater or less amount which may be produced in the year by the growers. The question of utility can be solved in reference to any article, by considering the real benefit or profit which men derive from it.

Within a few years, India Rubber has been employed for almost every variety of purposes. From being only used in erasing the pencil marks made by some drawing master or his pupils, it has run through almost the whole catalogue of domestic uses, until it has become a medium of light, and, if our genius do not desert us, will supersede all farther use of paper.

The various companies which have been organized for the manufacture of India Rubber, some of which have succeeded, have produced no article which promises more universal benefit than the Life Spar, recently invented by J. S. Armstrong, the enterprising agent of the Roxbury India Rubber Company. The consideration of the many serious accidents which have happened in consequence of the burning of steamboats, and in particular, the truly awful instance of the Royal Tar, which is still fresh in

our memories, has induced him to offer to the public the LIFE SPAR, of which we will attempt a description.

It consists of a long cylinder, fourteen feet and a half in length, and thirty-six inches in circumference, made of the strongest twine duck on its exterior, and lined with cotton drilling. The cloth, before making up, receives a coat of India rubber, which renders it perfectly air-tight. Two bands run from either end along its whole length, to which are attached twenty-four rings, of sufficient calibre to receive the arm of any individual who may be incapable of holding on with his hand. It is inflated with air by three tubes, one at each end, and one in the centre. Its weight, when inflated, is twenty pounds. It is capable of supporting thirty men in the water, although there are rings for only twenty-four. It may be packed with ease. in the top of a common sized travelling trunk. In case of accident on board a ship or steamboat, this article can be inflated in fifteen minutes by the breath of three men, or in less than half that time by the common valve bellows; and, being thown overboard, will afford almost perfect security to those who will entrust themselves to it.

There have been many inventions for this purpose, but none which answers the end so admirably. It is portable, and occupies but little space. Every steamboat on our waters should be supplied with it; and no ship-master or owner is justified, when the expense is so small, in suffering his vessel to leave port without one. They are for sale at the Roxbury India Rubber Company's store, No. 82 Washington Street.

G. T. D.