Miscellanies. 397 
PHYSICS. 
1. New Thermoelectric piles of Nobili.—The first of these, 
named pile a rayons, consists of a certain number of thermoelectric 
pairs of antimony and bismuth, disposed in rays around a common 
centre, and in the same plane. Each of the pairs terminates by a 
very fine point directed towards the center of the system, but suffi- 
ciently distant to isolate the plates. ‘The communications of one 
pair with another are established in the circumference by small arcs 
of bismuth or antimony soldered to convenient points, taking care so 
to complete the circuit, that the two elements, one of bismuth, and 
the other of antimony, remain free, and form the two poles destined 
to receive the wires of the galvanometer. ‘This assemblage is at- 
tached to a thin wooden disc, open in the middle, displaying the 
points, and the whole contained ina circular brass box, in two parts, 
also pierced in the center. In one of these last openings is adapted, 
in the direction of the axis, a brass tube closed at top except a small 
hole in the center, through which can be seen the center of the pile. 
This hole should be so small as to prevent the heat of the eye from 
acting on the pile, and may be closed with a thin plate of mica or 
gypsum. The box has a vice on its side to attach it to any sup- 
port. ‘To govern the access of the heat to the thermo-electric 
points, a movable sector, pierced with several groups of small holes 
of different diameters is attached to the central opening in the bot- 
tom of the box. 
The advantages of this pile over others, are, greater intensity, the 
number of elements being equal, feels the influence of caloric, and 
returns to its previous temperature more rapidly ; through the cen- 
tral openings may be seen the luminous effect when accompanied 
by a calorific effect ; and it is adapted peculiarly, besides all ordina- 
ry uses, to researches whose object is the concentration of calorific 
rays. 
Some experiments made with this instrument.—1. M. Nobili finds 
that radiant heat is not polarized in traversing the tourmaline, nor by 
reflexion, nor upon ordinary polarizing surfaces, nor upon metallic 
surfaces. 2. He caused the rays from a cube of hot iron (not red) 
to traverse a lens of rock salt, and concentrated them into a focus, as 
luminous rays. 3. He substituted for the iron, the flame of an ar- 
gand lamp, and placed before the opening of the pile a small metal- 
lic obstacle just large enough to intercept the luminous rays, and ob- 
