III. PHYSICS AND PHYSICAL APPARATUS.--Seyfferth's Pyrometer. 7 figures.--Pyrometer with electric indicator.--Method of mounting by means of a cone on vacuum apparatus.--Mounting by means of a sleeve.--Mounting by means of a thread on a tube.-- Mounting by means of a clasp in reservoirs.--The pyrometer mounted on a bone-black furnace.--Mounted on a brick furnace Delicate Scientific Instruments. By EDGAR L. LARKIN. An interesting description of the more powerful and delicate instruments of research used by modern scientists and their marvelous results The Future Development of Electrical Appliances. Lecture by Prof. J. W. PERRY before the London Society of Arts.--Methods and units of electrical measurements Researches on the Radiant Matter of Crookes and the Mechanical Theory of Electricity. By Dr. W. F. GINTL Economy of the Electric Light. W. H. PREECE'S Experiments Investigations On the Space Protected by a Lightning Conductor. By WM. H. PREECE.--5 figures Photo-Electricity of Fluor Spar Crystals The Aurora Borealis and Telegraph Cables The Photographic Image: What It Is. By T. H. MORTON. 1 figure.--Section of sensitive plate after exposure and during development Gelatine Transparencies for the Lantern An Integrating Machine. By C. V. BOYS.--1 figure Upon a Modification of Wheatstone's Microphone and its Applicability to Radiophonic Researches. By ALEX. GRAHAM BELL,--2 figures IV. ARCHITECTURE.--Suggestions in Architecture, 1 figure.--A pair of English cottages. By A. CAWSTON * * * * * ALCOHOL IN NATURE--ITS PRESENCE IN THE EARTH, WATER, AND ATMOSPHERE. A Chemist of merit, Mr. A. Müntz, who has already made himself known by important labors and by analytical researches of great precision, has been led to a very curious and totally unexpected discovery, on the subject of which he has kindly given us information in detail, which we place before our readers.[1] Mr. Müntz has discovered that arable soil, waters of the ocean and streams, and the atmosphere contain traces of alcohol; and that this compound, formed by the fermentation of organic matters, is everywhere distributed throughout nature. We should add that only infinitesimal quantities are involved--reaching only the proportion of millionths--yet the fact, for all that, offers a no less powerful interest. The method of analysis which has permitted the facts to be shown is very elegant and scrupulously exact, and is worthy of being made known. [Footnote 1: The accompanying engravings have been made from drawings of the apparatus in the laboratory of which Mr. Müntz is director, at the Agronomic Institute.] [Illustration: FIG. 1.--FIRST DISTILLATORY APPARATUS.] [Illustration: FIG. 2.--SECOND DISTILLATORY APPARATUS.]