732 



SCIENCE. 



[N. S. Vol. VIII. No. 204. 



personal equation from other forms is very 

 considerable. When the Greenwich cata- 

 logue for 1890 is published, it will be neces- 

 sary to find out in some manner the per- 

 sonal error depending on magnitude of the 

 chronographic right ascensions of that cata- 

 logue, but these will have in them a per- 

 sonal element depending on the habits of 

 the observers by whom the transits have 

 been registered, and this will be complicated 

 unless it is shown that the various observ- 

 ers have been brought to a more uniform 

 habit than is generally supposed. The 

 comparison of the catalogue for 1890 with 

 the zones of the A. G. C. will at a later 

 time furnish a great amount of interesting 

 information, but which at present needs the 

 careful study of the methods of observa- 

 tion and elements of reduction which have 

 been employed in the zones already observed 

 by eye and ear as well as by chronograph. 



The catalogue of Dr. Komberg* is the 

 best standard of comparison for the A. G. 

 C. eye -and- ear zones, as it was observed in 

 the years 1874 to 1880 with a powerful 

 meridian circle whose aperture was large 

 enough to render all the A. G. C. stars dis- 

 tinctly visible, and the standard of reduc- 

 tion is the same as for the A. G. C, viz. : 

 Wagner's right ascensions for 1865 and 

 Nj'ren's declinations for the same epoch. 

 Truman Henry Safford. 



Williams College. 



S03IE DANGERS OF TEE ABUSE OF CHEM- 

 ICAL FORMULAS. 



When Thomson made his memorable 

 visit to Dal ton, in Manchester, nearly one 

 hundred years ago, and w^as shown the sys- 

 tem of symbols by which Dalton hoped to 

 make clear his ideas as to atoms and their 

 combinations, he was enthusiastic as to the 

 future usefulness of such a system. And, 

 although the system was clumsy and inade- 



* I regret to say that this excellent observer has 

 passed away since these words were written. 



quate to the task of properly representing 

 the great mass of chemical facts, it con- 

 tained the valuable idea of graphic repre- 

 sentation which was to be ingeniously 

 elaborated and developed by later masters 

 of the science. 



It was through Berzelius next that chem- 

 ical sj'mbols were made simpler and clearer. 

 So manifest was their usefulness that they 

 speedily claimed the additional advantage 

 of almost universal acceptance. Local 

 adoption onlj^, the use by chemists of one 

 nationality or the followers of one master 

 would have proved a most serious bar to 

 the advancement of the science. We can 

 fancy the confusion which would arise from 

 the use of dififerent systems at present, but, 

 happilj', such a picture exists in the imagi- 

 nation only. The science has one univer- 

 sal language of symbols which those of 

 every tongue can read and understand. 

 The advantages of such a system need not 

 be dwelt upon. I purpose rather pointing 

 out a few possible dangers and abuses. 



The simple application of symbols in the 

 time of Berzelius has become more compli- 

 cated as the science has developed and the 

 knowledge of both composition and consti- 

 tution of chemical bodies has increased. 

 Intended at first to represent elements and 

 single compounds, the symbols have been 

 developed into complex formulas, and these 

 have been united into algebraic equations 

 in the effort to make them represent as 

 much as possible of the knowledge so 

 laboriouslj' acquired by multiplied experi- 

 ments. The system has become in truth 

 the shorthand of chemistry. 



While its great usefulness is not to be 

 underestimated, the limitations of the sys- 

 tem should be duly recognized. In the 

 first place, it can only partially represent 

 the mathematical relations of the science. 

 Again, there is no mode of indicating in an 

 equation the physical forces which always 

 accompany chemical reactions. These re- 



