658 Transactions of tee American Institute. 



magnetism used in making iron. 

 The London Athenaeum says, among the many new applications 

 of electro-magnetism to the arts and manufactures, is that of making 

 it instrumental in the smelting of ore. A fixed electro-magnet is 

 placed opposite an opening in the side of the furnace containing 

 the metal to be smielted, and a current of magnetism is directed 

 on the molten metal. The effect on iron is said to be very remark- 

 able, rendering it hard and tough. The process is carried on with 

 great success at one of the most important iron works in Sheffield. 



POPULATION. 



The total population of the earth has been estimated at between 

 1,200,000,000 and 1,300,000,000 persons. Assuming that 32,000,- 

 000 die annually (says The London Lancet), the deaths each day 

 would be nearly 88,000; 3,600 per hour, sixty per minute; and 

 thus every second would carry into eternity one human life from 

 one part of the world or another. But reproduction asserts its 

 superior power; for, on calculating the probable annual births on 

 the globe, the result shows that whereas sixty persons die per 

 minute, seventy children are born in the same time, and thus the 

 increase of population is kept up. 



THE FUNCTION OF CHLOROPHYIX. 



Dr. F. Cohn, of Breslau, maintains that chlorophyll, or some 

 closely allied body, is contained in all growing plants, and is the 

 principal actor in the process of assimilation; and further, that the 

 quantity present in the lowest forms of plants and animals, controls 

 their motion. They always approach the light, and if various 

 colors are present, they move toward the dark blue or violet in 

 preference to the red, showing that the actinic rays exert more 

 power in this respect than the thermal. If one-half a fragment of 

 chalk is coated over with a resinous substance, and placed in dilute 

 acid, the evolution of carbonic acid from the exposed surface will 

 cause the coated portion to be projected foremost. Dr. Cohn con- 

 cludes that, in a similar way, the chemical action resulting from 

 chlorophyll, when subjected to light, may produce those axial 

 rotations sometimes manifested as longitudinal motion. 



METROCHROaiE. 



This is an instrument for detecting and estimating the changes 

 of star-colors. As yet, the only changes noted with certainty are 

 in Sirius and 95 Herculis. Heretofore the great difficultv has been 



