INSTRUMENTS AND METHODS OF RESEARCH. 107 
kalisches Worterbuch — the revised edition by the noted in- 
vestigators Brandes, Gmelin, Horner, Littrow, Muncke, and 
Pfaff, in 20 volumes and published in Leipzig, 1825-1845. 
A veritable fund of information is found under the headings 
“Beobachtung” (observation) and “Versuch” (experiment). 
The article on “Beobachtung,” by the physicist Muncke, 
embraces 28 octavo pages. lie shows the distinction between 
“Beobachtungen” (observations) and “Versuche” (experi- 
ments) to be that the former pertain to the perceptions of 
phenomena presented to us by Nature in her unmodified 
course, whereas in the latter — in the experiments — we are 
seeking to produce certain results or phenomena, more or 
less looked for, in order either to verify a law already known 
or to disprove one suspected of being wrong or even to dis- 
cover a new one. Both classes of experiences are necessary 
for a piece of investigation or research work. 
Thus, we may behold either visually or in some other way 
certain striking solar phenomena; these belong to the class 
of observations which we ourselves are unable to modify in 
any manner whatsoever. Continued observation may, how- 
ever, reveal a certain law which by experiment in the labora- 
tory, conducted along more or less definite lines, we may 
seek to imitate in the hope of getting some clue to the modus 
operandi of the observed phenomena. In this article on 
“Observations” the author treats in detail the various ele- 
ments entering into correct methods of investigation, condi- 
tion of the observer and of his senses, his being unbiased, 
character and errors of the instruments, errors of results, 
methods of increasing accuracy, representations of observa- 
tions by graphs and formulae, method of least squares, etc. 
He points out the mistake sometimes made, that an estab- 
lished formula satisfying the observed phenomenon within 
certain limits represents an actual law of nature. 
The article “Versuch” (experiment) consists of 44 pages 
and is contributed by the astronomer Littrow. Lie shows 
that the most rapid development takes place in those sciences 
which afford the greatest opportunity for experimentation, 
referring, e. g., to the slow and painful progress of the astron- 
