November 19, 1886.] 



SCIENCE. 



449 



T, Sterry Hunt read a paper on ' A basis for 

 chemistry.' Herein he resumed the conclusions 

 of a series of papers on chemical philosophy from 

 1848 to 1886. He defined chemical changes as 

 interpretation or differentiation resulting in new 

 species ; distinguished in the chemical process 

 metagenesis and metamorphosis, the latter embra- 

 cing homogeneous changes only ; sought to define 

 the limits between chemistry and dynamics, and 

 to exchide the atomic hypothesis from the former ; 

 discussed the genesis of chemical species from 

 a primal element ; maintained that not only sohi- 

 tion but fusion, solidification, volatilization, and 

 condensation are chemical processes, liquid and 

 solid species bemg polymers of their x-espective 

 vapors ; and showed that the law of homologous 

 or progressive series extends to mineral species, 

 as oxides and silicates, which are not only of 

 high equivalent weights and complex formulas, 

 but are polymers whose degree of condensation it 

 is possible to fix. The values got by dividing the 

 received equivalents (hydrogen being unity) by 

 the density (water being unity) represent, not the 

 volumes of molecules, but the contraction in pass- 

 ing from the gaseous to the solid or liquid state, 

 being the reciprocals of the coefficients of con- 

 densation. Water, whose density at +4° is 1.000 

 (being formed by the condensation of 1,638 vol- 

 umes of steam at 100°, with an equivalent weight 

 of 17.9633, to a single volume at the same temper- 

 ature), has itself an equivalent weight of 29.244 in- 

 stead of 29.304 (which corresponds to HgO = 18), 

 as given by the author in Science for Sept. 10, 

 1886. From this figure the equivalent weights of 

 all spheres whose specific gravities are known 

 may be calculated ; the law of volumes being 

 universal, and extending alike to gases and 

 vapors, to liquids and solids. 



F. W. Putnam, in a paper on ' Archeological 

 explorations in the Little Miami valley,' illustrated 

 by elaborate drawings and photographs, showed 

 that the exhaustive method adopted during the 

 past five years is the only one that can possibly 

 give I'esults of any value relative to the early oc- 

 cupants of this continent. Professor Putnam's 

 researches show that there have been at least two 

 types of people, — first, those whose graves are 

 the so-called ash-pits ; second, those who built 

 great mounds over the remains of their chiefs and 

 great leaders, while the mass of the common people 

 were buried in trenches lately discovered by him. 

 Both these occupied the central regions, and were 

 spreading northward when they were met and 

 overthrown by the Indian races of modern times, 

 who have spread from east to west. Professor 

 Putnam's paper was but a small selection from 

 the large volume now preparing by him. 



E. C. Pickering read a paper on the ' Draper 

 memorial photogra^jhs,' in which he stated that 

 photographs of the spectra of the stars had been 

 studied by himself fii'st with a small telescope, the 

 exposures lasting generally five minutes, next with 

 a larger telescope, and finally with the magnifi- 

 cent eleven-inch glass belonging to Dr. Draper, 

 and loaned by his widow, in front of which are 

 placed two wedges or prisms of glass eleven 

 inches square, and whose construction must be 

 considered as the greatest triumph hitherto at- 

 tained by the opticians. With this latter appa- 

 ratus, which has now been in operation only a 

 few weeks, photographs of the stellar spectra 

 have been made by exposures of from five minutes 

 up to one hour. The bright and dark lines in* 

 these photographs, as shown by high magnifying 

 powers, are to be counted by hundreds testifying 

 to the wonderful perfection of the optician's work, 

 and give us for the first time assurance that the 

 problem of the movement of the fixed stars to and 

 from the earth can now be attacked with hopes 

 of success. By means of the lantern. Professor 

 Pickering showed upon the screen the result of 

 some of his most recent photographs, among 

 them the entire group of the Pleiades, in which 

 the agreement among the spectra of certain stars 

 strongly confirmed the results announced by Dr. 

 Elkins as to their physical connection. 



C. Abbe, in a paper on ' The question of barom- 

 eter exposure,' stated that the influence of the 

 wind upon the barometer is not a new question, 

 but has long since been recognized as an impor- 

 tant matter. Its actual treatment had, however, 

 been so difiScult as to lead to its neglect. This is 

 one of a series of difficult questions in aero- 

 dynamics which are intimately connected with 

 each other. For instance : the rain-gauge is an 

 obstacle to the wind ; the currents about its 

 mouth deflect the rain ; the proper gauge must be 

 so constructed that there shall be no cmrents 

 about its mouth ; the best gauge has the least de- 

 flection. On the other hand, a cowl on a chim- 

 ney-top to increase the draught or ventilation is 

 an obstacle to the wind, so arranged that it shall 

 give the greatest disturbance : its province is to 

 diminish the static pressure at the top of the 

 chimney, and allow the static pressure in the 

 room below to push the air upward. Elaborate 

 experiments on this subject were made in Boston 

 in 1848, and the apparatus is stiU preserved by 

 the chairman of the committee, Dr. Morrill Wy- 

 man : illustrations of their results were given by 

 the author. The problem of measuring the force 

 of the wind is very distinct from that of measur- 

 ing the velocity, since the force varies with the 

 shape of the obstacle and its size. Illustrations of 



