SEPTEMBER 29, 1899. ] 
and not chiefly retinal, and that our opera- 
tion of vision has been developed by evolu- 
tion to that which is necessary for conveni- 
ence and self-preservation. 
The two papers by Mr. Wead were of 
special interest from the historical point of 
view, presenting on the one hand, with con- 
siderable elaboration, the development of 
the organ pipe as seen in the various in- 
structions as to their manufacture, length 
and other dimensions ; incidentally the per- 
fection of the organ pipe at any particular 
era, of course, enables us to judge to some 
extent as to the musical conditions existing 
at that time. In the study of the literature 
of the musical scale, much interesting in- 
formation has been obtained with reference 
to the so-called Arab scale, extant descrip- 
tions of certain Arab musical instruments, 
such as the lute, the tambour of Bagdad and 
others, enable us to see the way in which 
the musical scale was built up, and how, in 
many cases, the interpolation of a note in 
the scale was determined, not by conditions 
of harmony, but by the dimensions of the 
neck and the location of frets upon the in- 
strument in use. 
A thoroughly new phenomenon in con- 
nection with the effect of an alternating 
current of electricity upon the human sys- 
tem was presented by Dr. Scripture. He 
has found that when the alternations in a 
current of electricity become as frequent as 
5,000 per second, the nerves of the part 
affected cease to react to pain, that is, a 
high frequency alternating current, instead 
of producing the muscular contraction 
brought about by lower frequency, pro- 
duces a local anesthesia or rather analgesia ; 
the current should be sinusoidal with equal 
positive and negative phases. Experiments 
have been tried in sending the current 
along the superior maxillary nerve with a 
view of cutting off the teeth from connec- 
tion with the brain; as yet, however, the 
frequency has not been high enough to ob- 
SCIENCE. 
439 
viate contraction of the facial muscles. It 
would appear that in this phenomenon we 
have a very valuable contribution to the 
inethods of surgery. 
Messrs. Carhart and Guthe have con- 
tinued their absolute determination of elec- 
trical units, and now offer the valve 1.4333 
volts at 15° C. as the electromotive force of 
the standard Clark Cell. 
In Mr. Trowbridge’s paper on the co- 
herer, we have a praiseworthy endeavor to 
present quantitative results, instead of hap- 
hazard observations upon this instrument 
which has recently become so important. 
Using a coherer consisting of 22 hard steel 
balls in a glass tube, he was able to dis- 
cover the conditions of current and pressure 
necessary for the operation of a coherer ; he 
found, for example, that a minimum electro- 
motor force of from 8 to 10 volts is neces- 
sary to break down the resistance of the 
coherer, but that after the resistance had 
been broken, subsequent discharges do not 
reduce the resistance much further; it thus 
would appear that it is the first rush of the 
electricity through the coherer which pro- 
duces the result, and that subsequent dis- 
charges are without useful effect ; that is, 
an oscillatory discharge is not necessary, a 
single impulse is sufficient. This observa- 
tion explains much of the confusion that 
has puzzled workers in wireless telegraphy. 
In No. 12 and No. 16 were presented ob- 
servations and conclusions with reference 
to the complex operations that take place 
in an electrolytic cell. The relations be- 
tween polarization, capacity and resistance 
being an extremely puzzling question. 
In No. 13 was presented the fact that a 
magnetic field surrounding an alternating 
current are tends to flatten the top of the 
electric wave and to increase the efficiency. 
A similar effect is produced by an aluminum 
electrolytic cell where the formation of a 
film of oxide acts like the dielectric of a 
condenser, and reverses the phrase. 
