392 Franklin Institute.

ing aug problem presented. Mr. Plotts exhibited specimens of his method and illustrated the facilities which it gives.

Mr. M. T. W. Chandler called the attention of the members to a very beautiful model of a weigh-lock, on the plan of Messrs. Ellicott & Abbott 's platlbrm scale, which is now under examination by the Committee on Science a~ld the Arts. The crib on which the boat rests while being weighed, is sustained by rods which operate on a series of steelyards, arranged longitudinally on each side of the lock. Fram these the strain is transferred by means of a rocking shaft, to another steelyard, placed above the lock and transversely to it, on which Ihe weighing is effected.

Dr. Hare communicated to the society some inferences and facts tending to explain the contradictory impressions which have existed respecting the competency of fused nitre to explode with water or carbonaceous combustibles. As his remarks were of great interest and importance, and cannot be condensed within the limits which we have at our disposal now, we refer our readers to the next number of the Journal, in which they will be given in full.

C O M M I T T E E ON SCIENCE AND T H E ARTS.

Report on Lieut. 8telwagon's Coast Surve2/ Sounding Jlpparatus. The Committee on Science and the Arts, constituted by the Franklin Institute of

the State of Pennsylvania for tile promotion of the Mechanic Arts, to whom was referred for examination--The Gedney Coast Survey Sounding Apparatus, invented by Lieut. H. S. Stelwagon of the United States Navy', Report--

That they have carefill]y examined this instrument, and made several experimental trials with it which have been very saris- iactory. It differs from tile ordinary deep sea lead, in having a pro- jecting stem of iron fixed in the lower end, which carries a conical iron cup screwed upon its lower extremity. A disk of leather slides upon the stem between the cup and the end of the lead, forming a valve which rises when the lead is passing down through tile water, and allows the conical cup to receive portions of the soil into which it penetrates ou reaching soundings, and fails upon the cup when it is drawn up so as to preserve its contents from being washed out as it passes rapidly through the water. Upon unscrewing the cup after a throw of the lead, a small pol'tion of the bottom soil is found securely lodged within, having exactly its natural proportions of fine and coarse particles unchanged by washing.

The Committee has no hesitation in commending this instrument, as much superior to the orditmry lead, both for scientific and ordinary maritime purposes, and its simplicity is such, that any" one capable of using the common lead, can use this with equal facility and with more certain and satisfactory results.

By order of the Committee. WILLIAM HAMILTON~ ~2cluary.

Philadelphi% Feb. 10~ 1848.