172 Art of f Travel.
making contrivances at hand, it is very difficult for him to obtain it. And further, though sparks, of their own accord and in the most unlikely places, too often give rise to conflagrations, yet it requires much skill and practice to succeed without fail, in coaxing a small spark into a serviceable camp fire. Therefore every traveller should carry on his person the means of procuring a light, under ordinary circumstances of wind and weather ; that is to say, he should have in his pocket, a light handy steel, a flint or an agate, and amadou or other tinder. I also strongly recommend that he should carry a bundle of half-a-dozen fine splinters of wood, like miniature tooth-picks, thinner and shorter than lucifermatches, whose points he has had dipped in melted sulphur; also a small spare lump of sulphur of the size of a pea or bean, in reserve. The cook should have a regular tinder-box, such as he happens to have been used to, and an abundance of wax lucifers. Paper fusees are not worth taking in travel, as wet entirely spoils them.
There are usually three separate agents in making a fire, each of which may be varied in many ways and requires separate description. 1. The Spark or other light to start with. 2. The -Tinder ; that is, some easily ignited and smouldering substance. 3. Fuel, judiciously applied to the burning tinder, or other feeble light, so as to develope it into a serviceable fire.
To obtain Fire from the Sun.-Burning-glasses.-The objectglass, and every other convex glass of a telescope, is a burningglass, and has only to be unscrewed to be fit for use. The object lenses of an opera-glass are very efficient. The larger the glass and the shorter its focus, the greater is its heating power. Convex spectacle glasses and eye glasses are too small and of too long a focus to be used with effect, except when the sun is very hot. An old-fashioned watch-glass, filled with water, and having the rays of a powerful sun glittered down upon it vertically by help of a mirror, will give a light. Dr. Inane and other arctic travellers have made burningglasses of ice.
Reflectors.-The inside of the polished metal cover of a hunting-watch will sometimes converge a sufficiency of rays,