3. Circulars of Information of the Bureau of Education. Nos. 2 and 1880. From the Commissioner. Patent Office Reports. Agriculture, 1854-1856 and 1858 and '59. Mechanics. Vols. 1 and 2. 1855. Catalogue of British Section of the International Exhibition. Philadelphia. 1876. Catalogue of Chinese Imperial Maritime Customs Collection at U. S. International Exhibition. Philadelphia, 1876. Der Buchhandel und die graphischen Künste Deutschlands auf der Weltausstellung zu Philadelphia, 1876. Catalog de los Expositores de España. Philadelphia, 1876. Mortality Statistics of the Census of 1850. From Dr. Carl Hering, Philadelphia. Speeches and Forensic Arguments. By D. Webster. Boston, 1880. Journal of Franklin Institute, 1837 and 1838. The Bible in Spain. G. Burrow. 1843. Patent Office Reports, 1851 and 1852. Diplomatic and Official Papers of Daniel Webster. 1848. Elements of Surveying. C. Davies. 1836. Treatise on the Principal Mathematical Instruments. By F. W. Summs. Life of Galileo. 1835. From B. B. McKinley. Second Treatise on Decrease of Water in Springs, Creeks and Rivers. From Chief of Engineers, U. S. A. Mr. Tatham announced that a life-size crayon portrait of the late Secretary, Mr. J. B. Knight had been made during the summer, and he would be pleased to hear from any one on the subject. Mr. J. Snowden Bell offered the following resolutions which were adopted unanimously: WHEREAS, We, the members of the Franklin Institute, have heard, with great pleasure, that this institution has been presented with a portrait of its late Secretary, Mr. J. B. Knight, therefore be it Resolved, That we receive with thanks this pleasing memorial of Mr. Knight. Resolved, That we hereby request the proper authorities of the Institute to place this gift in some prominent position in the rooms of the Institute, as a fitting tribute of respect to the memory of one who so earnestly labored in behalf of the purposes of this institution. Mr. W. Barnet Le Van read a paper, illustrated by diagrams and drawings, on "The Weakening of Steam Boilers by cutting holes in the shell for domes and necks." He said that the weakening effect of cutting holes for domes or necks was proportioned to the section of the dome joining the shell, independent of the size of the hole cut, and expressed the opinion that domes should be discarded and boilers of slightly larger diameter, with perforated tubes, used, instead of boilers with domes. He cited instances of the successful use of locomotive and stationary boilers constructed without domes. He contended that manholes should never be cut in the shell if it was possible to avoid doing so, and described at length experiments made by the Manchester Steam Users' Association in 1876, in support of his statements. He referred to the bad record made by the "two-story," or "Rider" boilers, such as exploded in Cherry street in 1864, and the one at Wilt & Sons' mills, which burst last year. He considered the form dangerous, and doubted whether it was as economical as had been claimed, and also said that "outside of a radius of thirty miles of this city they are scarcely known." The boilers tested by the Manchester Steam Users' Association were analogous in construction to the "twostory," or "Rider" boilers. The diagram of a boiler containing the perforated pipe suggested by Mr. Le Van was thrown upon the screen, and some discussion arose as to the proper position of the pipes as shown in the diagram, in which Messrs. Cooper, Nystrom, Bell, Cartwright and Le Van participated. Mr. Bell called attention to an inaccuracy in the paper read by Mr. Le Van, which he had seen mentioned elsewhere, and that was in regard to the use some years ago on the Baltimore and Ohio Railroad of locomotives without steam domes. He had been connected with the road at the time mentioned (from 1860 to 1865), and they had at the time eight Mason engines, all of which had steam domes. Mr. Le Van said that there were some roads in England successfully using locomotives without steam domes. Mr. Orr, referring to a statement in Mr. Le Van's paper about a boiler which was being tested, and which, after standing a pressure of 149 pounds, burst at the addition of another pound, expressed the opinion that a safe limit of test should be adopted to prevent such explosions. Dr. Seiler exhibited and described a photophone, in which a ray of light, passing through perforations in a revolving disk, and being thus interrupted, transmitted a sound proportioned to the velocity of the disk, to any substance except carbon or fine glass. He also gave an account of Prof. Bell's experiments which led to the invention of the photophone. Selenium, in its crystalline form, when exposed to light, opposes less resistance to the passage of an electric current than when in darkness. Prof. Bell made a cell of selenium, and introduced it in the primary coil of an induction coil, the secondary coil being connected with a telephone. He then took a disk of silvered mica, condensed on it the sunlight, and throwing the reflected light, condensed by a lens, upon the selenium cell, made the beam of light and interrupted one by speaking against the mica disk, and setting up vibrations, which changed its form. The varying resistances offered by the selenium to the passage of the current resulted in movements of the disk of the telephone in circuit therewith, corresponding with the variations produced by speaking against the mica disk at the other end of the beam of light. The photophone had been tried at a distance of 900 feet-far enough apart to make it certain that the voice of the speaker could not be heard without the use of the photophone -and conversation had been successfully carried on. Dr. Seiler said that he had had satisfactory experiments with it over a distance of about sixty feet. He considered it an instrument of extreme scientific interest, but did not know whether it would be of any practical value. The medium of transmission is not heat, nor light in conjunction with heat, for an alum cell has been used to cut off the heat rays. In the simple instrument which he exhibited one could hear the sound of the interrupted beam of light without the use of the diaphragm, and that the sound was not an imaginary one could easily be tested by putting the hand in the beam of light, thus interrupting the sound. Mr. Cooper inquired why, with a mechanical arrangement of this kind, carbon or glass could not be used. Dr. Seiler replied that very little was known as yet about this new instrument. There are many obscure facts about its operation. All that observers can now do is to report facts as they find them, and it appears from experiments that some substances are better than others. He would not say that glass or carbon would not respond by sound to the interruptions of the beam of light, but only that they were not as good as some other substances-hard rubber for instance. Prof. Houston said that this was one of the most wonderful discoveries ever made. He had not had the advantage of seeing the experiments described in the garbled reports of newspapers, but he nevertheless felt competent to make a photophone from what he knew about the principles on which they are constructed. They may be aptly described as telephones without wires, the beam of light being, so to speak, the connecting wire. Some day, perhaps, we shall have the navigator getting into the beam of the lamp of a lighthouse, and, instead of looking at his chart, calling along the beam to inquire, "What lighthouse is that?" He again described the action of the photophone, with the aid of a diagram on the background, saying: Here you have a battery in the circuit of which more or less current flows according to the resistance. You put selenium in the circuit, and the resistance varies with the ray of light that falls on it. You put a telephone in the circuit, and the movement in the plate corresponds with the varying strength of the current. The most remarkable part of the discovery he considered to be the fact that cutting off the heat rays by an alum cell, and cutting off the light by a plate of rubber, yet something passed through which the interruptions of the light were made manifest by sound. There was something in this which suggested the fourth state of matter, for the illustration of which he saw some apparatus on the table. Mr. Walton, of James W. Queen & Co., exhibited Prof. Crookes' Tubes, now manufactured and sold by dealers in philosophical apparatus. These tubes are exhausted to about the millionth of an atmosphere, and this high vacuum has been supposed to present a fourth state of matter-something beyond the gaseous-and where matter behaves in an entirely different manner from anything heretofore known. Mr. Crookes says that in this fourth state of matter we have actually touched the border land where matter and force seem to merge into one another. Mr. Walton exhibited the "stencil tube," showing the shadow of a cross in the radiant matter, the "railway tube" showing the mechanical action of radiant matter, the electric-radiometer, etc. A resolution was adopted inviting Mr. Outerbridge to lecture on the subject during the winter. Among the novelties exhibited were Evans' Mercury Seal and Sewer Gas Trap, Wentworth's Saw Vise, Holt's Can Opener, McAlpin's Portable Oven and Grant's Revolving Water Filter. In this filter the globe containing charcoal, through which the water passes, can be turned upside down, so as to be readily cleaned of impurities. On motion, the Institute adjourned. ISAAC NORRIS, M. D., Secretary. he Metric System-Is it Wise to Introduce it into our Machine Shops? By Coleman Sellers, M.E...... 289 he Weakening of Steam Boilers by Cutting Holes in the Shell for Domes and Necks. By W. Barnet LeVan...... servations in Brazil. By W. Milnor Roberts, C.E... odern Steel as a Structural Material. By W. Worby Beaumont, C.E............................................................. 1 a Peculiar Behavior of Copper. By W. H. Preece........................ the Liquefaction of Ozone, and on its Color in the Gaseous State. By MM. P. Hautefeuille and J. Chappuis........... ....... 313 332 343 345 ITEMS. nish Engineering, 331. Siphons in Sewers, 347. Safety Paper, 350. Electric Light in the French Salon, 350. Maiche's Electrophone, 350. Magnesium in the Sun, 351. Punching Iron, 351. Printing Cable Dispatches, 352. Organic Synthesis, 353. Velocity of Steam Engines, 353. Philosophy of Welding, 353. Electric Adhesion of Metal Contacts, 354. Human Power for Short Intervals, 354. Heats of Combustion, 354. Collodion Tablets....... ......... 354 Philadelphia: FRANKLIN INSTITUTE, 15 South Seventh St. |