SCIENTIFIC SUMMARY. 
217 
■with the reproduction of the clang-tints of tones through the telephone. If 
in one of the two telephones a higher fork he substituted for the Ut 4 one 
and this is sounded with the fiddle-bow, “ there will be heard with another 
inserted telephone of the ordinary construction tones of even 12,000 double 
vibrations per second, a sign that the variations of the magnetic condition of 
a magnet perceptibly occur, even when the forces producing these variations 
change their size 24,000 times in a second.” In another case he used the 
telephone to test the electric vibrations indicated by Helmholtz and others 
as produced in the induced coil by the opening of the primary current of an 
induction apparatus, when the ends of the former are connected with the 
armatures of a condenser. The telephone was inserted in the circuit between 
the coil and the condenser. When the ends of the induced spiral were not 
connected with the condenser, he heard a dull report in the telephone ; when 
these ends were connected with the condenser, this report was accompanied 
by a shorter, higher sound. The observations were made with a telephone 
having a very thin and deep-toned iron membrane. 
At the meeting of the Academy of Sciences of Vienna, on February 14, 
Dr. J. Puley suggested another application of tuning forks to telephonic sig- 
nalling. He proposes to remove the vibrating plates from two connected 
telephones when not in action, and to place opposite the coils the limbs of two 
tuning-forks of as nearly as possible the same tone. On the other side of each 
tuning-fork is placed a small bell, and between this and the fork a little 
brass ball is suspended so as to touch the latter. When the fork at either 
• end is set in vibration by means of a small iron hammer coated with leather, 
the fork in the other station also vibrates, and sounds the bell by means of 
the little ball. When the signal is answered from the receiving station, the 
vibrating caps are put on the telephones, and conversation can be carried on. 
Dr. Puley has also made experiments with steel reeds, such as are used for 
the harmonium. With a resonance box, the tone is so strengthened at the 
receiving station as to be perfectly perceptible in a large room. The bell- 
signal is so loud as to be audible in an adjoining room with the door closed. 
The Ultra-violet Spectrum has been studied by M. Cornu in a paper 
brought before the French Societe de Physique, on February 15. He employs 
the ordinary ray from a prism of Iceland spar, which forms the more deviated 
.and the more widely dispersed of the two spectra. He replaces the glass or 
metal reflector of the Heliostat by a prism of quartz giving total internal 
reflection. He uses quartz object glasses, ground specially for obtaining the 
minimum of aberration, the shape being that of a crossed lens, very nearly 
plano-convex, with its flatter curvature outwards. He concentrates the 
light on the slit by means of a convex lens also of quartz. It is thus found 
' that the spectrum varies with the time of day, having a maximum about 
midday. It is longer in winter than in summer. To obtain the normal 
spectrum, he draws all the lines of the prismatic spectra on a large scale, 
then determines the wave-lengths of some, and calculates the others by 
interpolation. He also employs diffraction gratings, but substitutes in this 
case the electric spectrum of iron for that of the sun, which is of feeble in- 
tensity in the ultra-violet tract. He has carried this region somewhat further 
than had been previously done. 
Lightning Conductors. — M. Melsens has erected a series of lightning- 
