228 
SYNTHETIC PHILOSOPHY. 
its image is similarly drawn upon the same paper. This 
scale upon the microscope drawing serves to measure the 
amount of magnifying, as directly and definitely as an engineer’s 
or architect’s working drawing is measured by the scale 
marked upon it. The accuracy of the whole is tested by 
checking the 10-100ths inch (or 1-lOtli inch) upon the micro¬ 
meter scale by comparison with an ordinary 1-lOtli inch 
rule. 
In the case of the l-25th inch objective there was not 
the means of applying the micrometer scale direct in this 
manner, and the measurement of the magnifying power w r as 
effected by using the rows of dots upon the above-named 
diatom as a comparative scale for measurement. A drawing 
was first made with a l-12tli objective of a portion of the 
diatom, and a measuring scale drawn upon it direct from the 
micrometer scale, and then a drawing of the same portion of 
the diatom was made with the l-25th inch objective; and 
by measuring the distances between the centres of the corres¬ 
ponding dots in the two drawings, the proportion between the 
magnifying power of the two objectives was obtained. The 
power of the l-25th inch objective with the lowest eye-piece 
is found to be 1470 diameters, with the middle eye-piece 
2280, and with the highest 8820 diameters. It performs 
well with the first and second eye-pieces, but breaks down 
in sharpness of definition with the highest eye-piece.* 
THE SYNTHETIC PHILOSOPHY. 
Students of the doctrine of Evolution, as set forth in the 
works of Mr. Herbert Spencer, will be interested to hear that 
a movement has been originated in Paris for the systematic 
study of the Synthetic Philosophy. The following gratifying 
letter, from Mons. James Grosclande, C.E., has been 
addressed to Mr. W. R. Hughes, F.L.S., President of the 
Sociological Section of the Birmingham Natural History and 
Microscopical Society, on the subject, to which a cordial 
reply has been made :— 
Paris, le 15 Juillet, 1887. 
Monsieur W. R. Hughes. 
J’ai recemment envoye une lettre a Mr. Herbert Spencer, 
l’eminent philosophe. Je lui f'aisais part de radmiration que 
* The objective described above is one presented to Mr. Marshall 
by the Exhibitors at the Bingley Hall Exhibition in connection with 
the visit of the British Association to Birmingham in September, 1886. 
Mr. Marshall was a member of the “Officers’ Committee” for the 
Exhibition. (Eds. M. N.) 
