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New industry in Madrid
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Correspondence.
[Jour. Frank. Inst.,
Protection of Water Pipes Against Rupture.--Messrs. B u y ton and Ross attach a special valve to the extremity of a water pi])% which can be opened automatically by electricity. They connect with it a thermometer~ which is so arranged as to close an ~fleetrie circuit when the temt)erature approaches the fi'eezing point. By the influence of the current a wedge is released which alh)ws the valve to t,fll into place and open the eml>tying fau<.,et.--Chron. Ldtt6'tr., Jan. 14, 1883. New Industry in M a d r i d . - - I n the neighborhood of the Puerta de Toledo, an establishment has been starte(l for the manu~aetm'e of artificial whalebone, from the horns of black cattle and buffah)es. It is said that the thctory is i>rovidcd with all modern improvement% and that its products are already coml>eting suece~sfhlly with similar articles which are imported fl'om abroad.--Gaceta l nd~zstrial, June 25~ 1883. C.
CORRESPONDENCE. Committee on Publication of the Journal q/the Franklin Institute.
GE~TIm~E~ :--On page 471 (December, 1883), Prof. L. D'Auria submits a new proposition, i. e., that the attraction is equal on all points of the level of' a liquid mass surrounding any solid body~ and bases his demonstration on the assumption (not clearly expressed in his letter~ but inferable i~om the conclusion he reaches) that the principle of equal transmission of pressure in hydraulics is such that the pressure is equal on all points having equal normal distance from the surface. I beg to refer the writer to "Theoretlsche Maschlnenlehre/~ by Dr. IP. Grashof, Leipzig, 1875. Chapter: Hydrostatics. The author defines: Level-surface within a fluid in equilibrium denotes any sur= face of' such a character that the resulting force of all attractions is in all points normal to the same. Then he demonstrates that level-surfaces are also surfkces of equal pressure, . . . and that if the external pressure on all points of a fi'ee surikee of' a fluid is uniform, this surface must be a level-surface as defined. The assumption in the correspondence referred to would therefore depend on the question whether or not all level-surfaces (surfaces of
Correspondence.
[Jour. Frank. Inst.,
Protection of Water Pipes Against Rupture.--Messrs. B u y ton and Ross attach a special valve to the extremity of a water pi])% which can be opened automatically by electricity. They connect with it a thermometer~ which is so arranged as to close an ~fleetrie circuit when the temt)erature approaches the fi'eezing point. By the influence of the current a wedge is released which alh)ws the valve to t,fll into place and open the eml>tying fau<.,et.--Chron. Ldtt6'tr., Jan. 14, 1883. New Industry in M a d r i d . - - I n the neighborhood of the Puerta de Toledo, an establishment has been starte(l for the manu~aetm'e of artificial whalebone, from the horns of black cattle and buffah)es. It is said that the thctory is i>rovidcd with all modern improvement% and that its products are already coml>eting suece~sfhlly with similar articles which are imported fl'om abroad.--Gaceta l nd~zstrial, June 25~ 1883. C.
CORRESPONDENCE. Committee on Publication of the Journal q/the Franklin Institute.
GE~TIm~E~ :--On page 471 (December, 1883), Prof. L. D'Auria submits a new proposition, i. e., that the attraction is equal on all points of the level of' a liquid mass surrounding any solid body~ and bases his demonstration on the assumption (not clearly expressed in his letter~ but inferable i~om the conclusion he reaches) that the principle of equal transmission of pressure in hydraulics is such that the pressure is equal on all points having equal normal distance from the surface. I beg to refer the writer to "Theoretlsche Maschlnenlehre/~ by Dr. IP. Grashof, Leipzig, 1875. Chapter: Hydrostatics. The author defines: Level-surface within a fluid in equilibrium denotes any sur= face of' such a character that the resulting force of all attractions is in all points normal to the same. Then he demonstrates that level-surfaces are also surfkces of equal pressure, . . . and that if the external pressure on all points of a fi'ee surikee of' a fluid is uniform, this surface must be a level-surface as defined. The assumption in the correspondence referred to would therefore depend on the question whether or not all level-surfaces (surfaces of