“January 28, 1897 | 
“method is exemplified by Nos. 1, 2, 3, 4, 6, 7, 10, 11, 12, 
13, 14, 17, 18, 20, 21, 24, 26, 28, 32 ; the second system, 
by the adoption of which instantaneous Réntgen photo- 
graphy became possible, is adopted in the tubes numbered 
5, 8, 9, 15, 16, 23, 25, 27, 29, 30; and the third principle 
is illustrated by Nos. 19, 22, 31. The Crookes’ tube, 
represented by No. 1, is very well known, and is still 
used for Réntgen photography on the continent. 
represents a form of tube used when the movement of 
the kathode stream by a magnet is desired, so that the 
rays can be made to impinge upon different parts of the 
glass. In No. 3, the concave kathode 
is brought very near to the glass, so that 
its focus is really outside. No. 4 shows a 
tube with a kathode which can be revolved in 
a plane at right angles to its own face. No. 5 
has two kathodes, and the rays from them 
are reflected from a platinum anode. In 
No. 6 the anode is formed of an aluminium 
disc, which is traversed by the kathode rays ; 
but the advantages of this form are not very 
clear. Two kathode streams are utilised in 
No. 7. The form of tube which workers in 
this country findygives the best results, is 
represented in No. 8, and is known as the 
“focus” tube, or tube of Jackson pattern. 
In this the kathode rays fall upon, and are 
reflected by, a platinum mirror which forms 
the anode. No. 9 has two anodes, one of 
NATURE 
297 
is constructed so that the platinum cone which forms the 
anode, reflects the rays from four kathodes placed around 
a circumference, and kept in action by as many coils. 
A tube, useful for showing the place of origin of active 
rays, is shown in No. 26. The next (No. 27) has two 
anodes and two kathodes ; the two kathode streams are 
| reflected from the anodes, and, meeting one another, are 
No. 2 | 
given additional power. No. 28 resembles No. ro, but 
it has the defect that it rapidly becomes heated. In No. 
29 the kathode is formed of an annular aluminium plate, 
the rays from which strike upon the central platinum 
them a hollow platinum cone which reflects 
the kathode rays. The tube shown in No. 10 
is especially suitable for use with currents 
of high frequency ; it is uni-polar, and has an 
external anode. No. 11 has pointed poles, 
either of which may be the kathode. The 
tube No. 12 has a platinum kathode, covered 
on its convex side by a glass insulator so as 
to reduce the loss of radiation. No. 13 is found 
to give good effects on fluorescent screens. 
No. 14 is for use with currents of high fre- 
quency, and has only one pole in the tube. 
No. 15 is a useful form of tube, one of its 
advantages being that two photographs can be 
taken at the same time by the reflection of 
the rays from the kathode on either side. In 
the tube represented by No. 16, a circular 
disc forms the kathode, and at its centre is 
set a hollow cone of platinum as an anode. 
No. 17 represents a form of tube for the invest- 
igation of the action of kathode rays upon 
a substance. The end of the cylinder is made 
so that substances can be introduced into the 
tube. Another kathodic cylinder is shown in 
No. 18 ; the kathode is situated at the place 
usually occupied by the anode, the latter pole 
being at the top. No. 19 combines the 
actions of both the’ direct and reflected rays. 
The kathode passes through a concave anode 
of platinum, and all the rays emitted by it are 
utilised either directly or after reflection. A 
cylinder employed at the commencement of 
_work with kathode rays is shown in No. 20; 
a good point about it is that the poles are some 
distance apart, so there is little fear of sparking 
outside the tube. A cylinder with an interchange- 
able window opposite, the kathode is represented in 
“No. 21. A tube with two anodes (No. 22) is designed 
‘on the principle of the reflection of the kathode rays, the 
kathode being placed centrally inside a reflecting anode. 
Another bi-anodic form is the large bulb shown in No. 
23. The next figure (No. 24) has slips of aluminium as 
poles, and either of them may form the kathode. No. 25 
NO. 1422, VOL. 55 | 
|_ 
Fic. 1.—Korms of tube used for the production of kathode and X-rays. 1, 2, Crookes’ 
tube ; 3, Séguy tube ; 4, Wood tube ; 5, Séguy tube; 6, Chabaud and Hurmuzescu 
tube; 7, Séguy tube; 8, “Focus” tube; 9, Séguy tube; fo, d’Arsonyal tube 5 
11, Séguy tube; 12, Puluj tube; 13, Séguy tube; rq, d Arsonval tube; 15, Le 
Roux tube; 16, 17, 18, Séguy tubes; 19, Rufz tube; 20, Crookes’ tube ; 21, 22, 23, 
Séguy tubes; 24, Rontgen tube; 25, Brunet-Séguy tube ; 26, 27, Le Roux tubes ; 
28, Colardeau tube; 29, Séguy tube; 30, Colardeau tube; 31, Séguy tube; 32, 
Réntgen tube. 
Se 
cone and are concentrated to a point by reflection. No. 
30 is designed to show the effect of the reflection of 
kathode rays in a space as small as possible. The tube 
has an electrode of palladium. The tube No. 31 1s very 
good for use with fluorescent screens, the kathode 
rays being reflected from a large anodic surface, 
with the result that the phosphorescent area of 
the glass is exceptionally great. The.tube shown 
in No. 32 represents the first form used by Prof. 
Ro6ntgen. 
