The proper size of the platina wire is the 1/100th part of an inch: a larger one will only yield a dull, red light, and a smaller one is difficult to use. About 12 turns of the wire will be sufficient, coiled around any cylindrical body suited to the size of the wick of the lamp; and four or five coils should be placed on the wick, and the remainder of the wire above it; and which will be the part ignited. A wick, composed of twelve threads of the ordinary sized lamp cotton yarn, with the platina wire coiled around it, will require about half an ounce of alcohol to keep it alight for eight hours. An agreeable and slightly acid smell arises from this lamp during its ignition. It is perfectly safe, as nothing can fall from it; and its novel appearance, in a wick's keeping red hot for such a length of time, is very surprising to persons unacquainted with its nature. P.S.--When the wire has become oxided, it will be necessary to uncoil it, and rub it bright again with fine glass-paper; which will cause it to act again with increased effect. REMARK. Such wire as is here described may, probably, be obtained in Philadelphia. FOOTNOTES: [17] In using the word "pit," instead of "mine," I have accommodated my language to the custom of the country. [18] Since the above article was written we have received some as large as a finger. [19] The green earth of most mineralogists. EDITOR. [20] _Formation_--a geological phrase, of German origin. [21] Doubtless the pea ore of the Wernerians. EDITOR. [22] This jet of cold water being let into the cylinder itself, necessarily cooled it at every stroke; and then it was necessary to heat it again to the boiling point, before the piston would reascend, and thus a vast loss of heat occurred. EDITOR. [23] But it is not necessary (as in the plate) to crowd the engine into the after-part of the boat, the boilers maybe placed forward, and near them, or over them, _the cylinder_, &c. The power is then communicated to the stern-wheel by a long shaft, supported on, or immediately under, the deck. This arrangement gives room for loading both behind and before the boilers and engine, and equalizes the burden. This is the actual arrangement of the Merrimack boat. [24] It is found with very high steam that the source of supply must be above the _chamber_, or a small quantity of cold water introduced to condense the steam therein. [25] Taken from the Philosophical Magazine, and by that work from the Annales de Chimie and de Physique, for January, 1818.