396 t~ranklin I~slilule.

made in exactly two minutes, by the action of the propellers alone. This experiment was repeated, and her head again directed up the river, in 3 m. 2 s.; while the next half turn, to bring her again upon the downward course, occupied 2 m. 14 s.

In returning up the river the tide was favorable, but the passage was made against a stiff breeze from the N . E . From the flag-staff at Fort Mifflin to the Point House wharf, the run was made in 29 m. 17s., and from the Point House to the Navy Yard in 12m. 20s . - - total time, from Fort to Navy Yard, 41 m. 3os.; the engines making 50 revolutions per minute. The Committee had no means of ascer- taining exactly, for themselves, the pressure of steam employed; but were informed that it was 60 pounds to the square inch.

By order of the Committee, WILLIAM HAMV.TON, Actuary.

PhiTadelphia, Nov. 11, 1847.

Report on J. H. Schomacker ~ Co.'s Pianos.

The Committee on Science and the Arts, constituted by the Franklin Institute of the State of Pennsylvania, for the promotion of the Mechanic Arts, to whom was referred for examination an Improvement in Pianos, invented by Messrs. J. H. SCHOMACKER & CO., of Philadelphia, Pennsylvania, REPoaT:--

That they have examined the application to pianos of the inventions lately made and patented by J. H. Schomacker & Co., of which the following is a brief description :

The sounding-board, in these pianos, is constructed so as to be detach- ed from the sides of the Instrument, resting oil props, or supports, which are secured to the bottom of the case; one end of the sounding-board being made with a return, so that its whole length is virtually increased. This construction frees it entirely from the injuries which it would re- ceive from changes in the form of the case caused by the strain of the strings, or from the usual shrinking and warping of the wood used in construction, and gives it the fullest opportunity to aid in the vibration consequent upon the sounding of the string.

The result of their.examination, which has been carefully made, is, that Mr. Schomacker has, by his detached sounding-board, attained, in the tone of his pianos, a much greater degree of sonorousness and resonance than the Committee have before observed in other instru- ments of the kind. They are also of opinion that these pianos will be more durable than those made by the old principle, and that the in- ventor is deserving of much praise for introducing this improvement, which will doubtless accelerate the perfection which these instruments are gradually attaining.

With regard to the patent arrangement for candle-sticks, on the music-board, the Committee believe that it is a very convenient ar- r a n g e m e n t - n o objections can now be raised as to the danger of their

Report on Jennison's Diap/Iragrn Filler. 397

vibrating, as all the parts of contact are carefully and effectually lined with fe!ting.

By order of the Committee, WILLIAM HAMILTON, Actuary.

~PMladelp~ia, Nov. 1 l, 1847.

Report on IF. H. dennison's Diaphragm Filler.

The Committee on Science and the Arts, constituted by the Franklin Institute of the State of Pennsylvania, for the promotion of the Mechanic Arts, to whom was referred for examination the Diaphragm Filter submitted by W. H. Jz~N~- soN, of the city of New York, REPoRT:-

That they have carefully examined and experimented on the three varieties of filters submitted to them. Their experiments have beeu conducted with great care and have extended over a duration of nearly £0 months.

No. 1. The first filter of Mr. Jennison is in the form of a hollow truncated cone, attached to a similar cone by its base, thus forming a double cone, at each end of which is a female screw adapted to the male screws on the nozzles of our common hydrants ; within this is a double cone, attached at the place of junction to the external shell, and leaving a space between them varying in dimensions from a quar- ter of an inch to an inch. The internal cone is perforated with holes, to allow the passage of water and act as a colander. A conical cap of felt is attached, by its edge, to the ring forming the base of the in- terior vessel within which it plays loosely, and constitutes the filtering medium. The current of water passing through the upper colander is strained through the felt, leaving the coarser particles of sedimentary matter on its upper surface, and passes through the lower colander and nozzle into any vessel ready to receive it.

No. 2. The second filter contained,in lieu of the inner perforated dou- ble cone, two parallel circular plates of perforated metal, attached, at their edges, to the external shell, separated from each other, by a cham- ber filled withcompressed sponge previously reduced to small fragments. The shape of the external shell also, in some specimens, approximated to a spheroid, having nozzles with screws, as in the filter No. 1.

No. 3. The third filter contained sharp pure sand, exceedingly com- pressed, (in lieu of sponge, as in No. 2. *) and the perforated plates of zinc were covered, on their inner surfaces, with tinned hrass gauze wire sieves, of exceeding fineness. The compactness of the sand is further increased by burnishing the external shell. Several varieties of these sand filters were examined by the Committee containing strata of sand varying in fineness of grain. : The mode of using Mr. Jennison's filters is to screw them on to a water pipe; the water, when laid on, passes through the filter under pressure in very large 9uanlities, leaving upon it the coarser particles,

As the sponge and felt are subject to decay, Mr. J. has discontinued the manu- facture of filters containing these materials.

VET-. X1V, 3gv Szan~s.--No. 6.--Dsctt~z& 184 7. 34