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I applied the same process upon an extensive railroad in England, in the manufacture of coke, and obtained a great economy from the nondestruction of the fire-boxes and tubes by the sulphur. I also obtained at Manchester very satisfactory results, by employing coke thus prepared for the re-melting of iron in cubilot furnaces; the purified bars bearing 528 lbs., while the unpurified broke with 514 lbs.

For the Journal of the Franklin Institute.

Sall of Western Pennsylvania. By JAMES C. BOотH and T. H. GARRETT. The value of common salt for dairy purposes, preserving food, and for general use, and the singularly advantageous position of the salt springs or wells of Western Pennsylvania, issuing at the mouths of coal mines, led us to investigate the relative purity of some of the salt manufactured there, in comparison with foreign salt imported and largely employed on the coast. We subjected to analysis, Turk's Island, Liverpool ground Rock, and two samples of salt, coarse and fine, kindly furnished us by Mr. Lewis Peterson, of Salina Farm, near Tarentum, Pennsylvania, where and by whom the two samples were manufactured.

The following tabular arrangement of the results of analysis give a clearer comparative view of their relative purity and value:

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Beside these, the Turk's Island contains a little sand, of which the others only contain traces. The difference between them is evidently that the impurities in the Pennsylvania salt are chlorides, and in the others, sulphates of lime and magnesia. Since the chlorides are easily removed by washing, it is evident that the Pennsylvania salt might be brought to a state of absolute purity, if it were desirable or necessary. The salt manufactured by Mr. Lewis Peterson, bears a close comparison with the Liverpool ground Rock, and his fine variety surpasses it. Both of his varieties are 4 or 5 per cent. purer than Turk's Island salt.

Hints on the Principles which should regulate the Forms of Ships and Boats; derived from original Experiments. By MR. WILLIAM BLAND, of Sittingbourne, Kent.*

Continued from Vol. xxiv., page 420.


Since curves must be substituted for the straight line in the forms of the bottoms of all vessels of speed, as proved (see experiments 33, &c., chapter VII.), and in consequence a keel is indispensable, the midship From the London Civil Engineer and Architect's Journal, November, 1852.

section, but particularly the parts fore and aft of the same, will partake more or less of the elliptic and angle shape.

From experiments made subsequent to those already given in chapter XI., but not entered, and for the purpose of determining the perpendicular depth of the under-part of the keel at midships, from the load waterline of models with curved bottoms, it appeared that the depth to cause the greatest lateral resistance should not exceed the average breadth of half the beam measured at the points of equal distance between the midship and either end; unless the centre of gravity by means of heavy ballast, as lead, be made to descend proportionally with any addition to the depth of the keel.

Again, as the above average depth is requisite for lateral resistance, then the midsip form, and likewise the sections towards both head and stern, must be moulded into those shapes which will meet the object desired, with the least increase of displacement beyond the true one the vessel ought to possess when required for speed, as in table 4, chapter XV.

Let the above be exemplified in the models O, Q, and R, and the diagram here annexed will assist in explaining the meaning.

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A CBD represents the half part of the horizontal section of the model O, taken at the low water-line; C D being the midship, and E F, G H, the lines of the average beam.

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No. 2. Midship Section of Model O.-Scale, 1 inch to 1 inch.

Let A B DC be the midship section of the model O, when with the flat bottom; L I the depth as stated in Table 4, Chapter XV. Now, in order to give speed to the model, the curved form must be applied to the bottom, which will cause the model to sink deeper into the water than before, by a one-fourth part of LI (see Chapter XVI.), or to the dotted line A E B.

Again, let E F equal the average breadth of beam, and F the bottom. VOL. XXV.-THIRD SERIES.-No. 1.-JANUARY, 1853.


of the keel; but as every increase of the displacement beyond A B D C, will retard speed; yet the part of the dead wood and keel from I to F, require support; it can only be carried into practice by transferring a portion of the capacity, or displacement at and about C, to between I and F. To this end, let K bisect the straight line C I, and G bisect A C from G, and draw through K the straght line G K H. By Euclid, the triangles G C K, KI H, are equal, therefore their displacements are equal. But since the keel from H to F, will likewise need support, a curved brace may be applied from M to N, which will, however, cause some addition to the capacity; or the curve T M N, may be substituted. To obviate the evil of additional capacity in some measure, the space may be filled with ballast, which, being situated low, will assist to compensate, by increasing the stability, and in consequence admit of an addition being made to the sail sufficient for the wind to impel forward the extra weight with nearly undiminished speed. The angle at G may be rounded off or not, but as it is, the original stability will be diminished. by the removing of the triangle G C K, to the triangle K IH, because it is sufficiently evident on inspection that the assumed centre of the triangle KIH, from the perpendicular line E F, is less than R, the centre of the triangle G C K; therefore the power of buoancy to aid stability is proportionally reduced, and which will not be altogether met by the ballast in the triangles K I H, and M H N; the stability will again be lessened also, if the angle at G is rounded off.

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No. 3. Bottom Curves of Model O.-Scale, f-inch to 1 inch.

In this diagram (No. 3), A C is the load water-line, A B, B C, the bottom curves, and D E, E F, their union with the keel G H.






No. 4. Model O, from Head to Midship.-Scale, 4-inch to 1 inch.

Here is represented the part of the model situated between the head and the midship. A L the load water-line, A B the curve as A B in No. 3, B being the depth of E I in No. 2, and I K the curve at the depth of A G in No. 2, and CD the curve uniting with the keel G H. The curves I K, A B, C D, and the dotted one E F, are all parallel to each other, and which must be carried out along the bottom of the ship in planes perpendicular to the horizon, and parallel to the ship's longitudinal axis. With regard to the lines E M, C N, &c., they must be drawn parallel to the load water-line to form a wedge of the bows, as repeated

experiments, not entered, have determined this point over the bow curved alone; yet the outline of the said curve should be preserved wherever the lines touch, and made to take the concave form, with the express view of promoting speed, by assisting the raising of the bows over the waves, particularly of sailing vessels against the downward pressure of the wind on their canvass.

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No. 4, continued.-Model O, from Midship Section to Stern.-Scale inch to 1 inch.

Let L A be the load water-line, B A, F E, D C, the curves, and D C the one uniting with the dead wood and keel. In this part of a ship no lines parallel with the load water-line are necessary, indeed they would be hindrances to speed, as has been shown already in the experiments. But in order to strengthen the dead wood and keel, short braces placed at the angle of 45° may be employed where thought requisite, but the less the better.




No. 5. Midship Section of Model Q.-Scale, inch to 1 inch.

AIC is the load water-line, A B, BC, DE, EF, are the bottom curves, and G H, H K, the union with the keel L N; A R, GS, are parallel horizontal lines, as in No. 4, to form the wedge bow. The stern part, meaning from midship to stern, need not (as before stated) the horizontal parallel line, but the curved form preserved throughout. The concave of the horizontal lines, as mentioned in treating of the bows of the model O, cannot here be dispensed with.

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Let A B D C be the midship section of the model'Q, A B the load water-line, the depth being increased from E F to A B, as in diagram No. 2. NK the depth equal to the average breadth of half the beam of the model Q, taken as in the model O. It is seen in this instance, that the depth from I to K, is less than in No. 2; therefore the bottom may be preserved flat at the midship, with a straight or curved bracket, as it were, to support the keel, and continued fore and aft; or it may at once

take the form as shown in the diagram by the letters H Y X, X D being taken equal to I H, when the triangles H I Y, X D Y, will be equal. Instead, however, of either of these, the outline may be as the curve G LM H.

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No. 7. Midship Section of the Model R.-Scale, inch to 1 inch.

A B the load water-line, E T the depth of flotation, as in Table 4, Chapter XV., with the addition of one-fourth part of the 13ths, in consequence of the curved bottom, making the total or one inch; which, according to the scale above is half an inch, or B R; therefore, A B R G represents the true displacement. E K is the half part of the average beam (see diagram R, in Experiment 83), in which the straight lines A B, D F, denote them; but they being drawn on the scale of -inch to 1 inch, the average of the two, when doubled, will make it in the 4-inch scale, as the diagram above, equal to EK, K being the bottom of the keel.

It appears upon the right-hand part of the diagram, that in order to support the necessary depth of keel, as T K, it must either have the timber of the bottom framed at midship, as in the dotted straight line IB, or in the curved one B S V K. If in the former, then the displacement will be doubled when completed on both sides of the model, and take proportionally from the speed, as recorded in Table 3, Chapter XV.; if the latter, still the original displacement will be increased, but not equal in degree to the former. The keel, however, cannot do without support; therefore, of the two evils, the latter must be preferred whenever speed is to be gained.

The form on the left-hand side of the diagram, comprehended and denoted by the curve L M N I, is graceful and effectual with regard to the keel; but then the displacement, even on inspection, exceeds more than double (it must be admitted) the true displacement required, and therefore will take too much froin the speed, as evidenced in Table 3, Chapter XV., but would answer well if the vessel be intended for burthen instead of a yacht.

Further Observations.

In the models having their horizontal section at the load water-line, after the form of a bird or fish, as the sole, it is seen that the midship section or widest part, is situated at two-fifths of their length from the head, and three-fifths from the stern. This is Nature's law, in order to counteract and balance the extra resistance the forebody meets with against the air and water to what the aft body is subject. In Chapter III.

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