588 Chronicles of Scrence. {Oct., 
two pictures which can be united stereoscopically is limited in the 
horizontal direction by the fact that their centres must be as nearly 
as possible opposite the pupils of the eyes; in the vertical direction 
it is only limited by the angle of natural vision, which practically 
admits of the use of a picture nearly double as high as it can be 
wide. The aim of the inventors has been go to modify the mode of 
taking, and the instrument for viewing the stereograms, as to take 
advantage of this fact. Pictures adapted for the panoramic stereo- 
scope have been taken by Mr. Harding Warner, of Ross, the well- 
known photographer. When taken from great heights and viewed 
in this instrument, the patentees state that the pictures represent 
objects in a better relative proportion to each other than when in- 
spected in the old form of stereoscope. The instruments are manu- 
factured in a variety of forms and of elegant designs, to meet the 
requirements of the pictures; and the latter are printed by the 
argento-carbon process, so as to ensure permanency. 
M. Civiale has brought before the Société de Photographie some 
observations upon the employment of sulpho-cyanides in toning and 
fixing. He stated that in the summer of 1867 he fixed about 700 
positive proofs by means of potasstum and ammonium sulpho- 
cyanides. A print, one half of which had been protected from the 
light, the other unprotected, and which had been exposed for three 
months, showed only an uniform tint. This, however, only shows 
that this plan of fixing destroys the sensitiveness to ight of the 
silver compound on the surface of the paper. It speaks nothing for 
or against the lability of the pictures to fade when exposed to dark- 
ness and damp. 
Exrcrriciry.— Wiedemann and Franz have proved experimen- 
tally that the values obtained for the conducting power of metals and 
alloys, for heat and electricity, are identically the same. The truth 
of this statement was strikingly illustrated by Dr. Matthiessen in a 
lecture which he gave at one of the Friday Evening Meetings of the 
Royal Institution. Bars of gold and silver and some gold-silver 
alloys were fixed so that one end of all of them was in a hot-water 
box and the other end in the bulb of a small air-thermometer ; 
the depression in the columns of the liquid in the tubes of the air- 
thermometers then indicated the relative conducting powers (ap- 
proximately) of the several bars; and if through the tops of the 
columns of liquid a line be drawn, such line would form a curve 
similar to that referred to as obtained for the electric conducting 
power. That this is true was thus shown:—bBy the side of this 
apparatus was placed another of this construction. Into the bulbs 
of several air-thermometers were fixed wires of the same size and 
length, and of the same materials as were used in the heat-conduct- 
ing experiment. One end of each wire was soldered to one thick 
