46 REPORT—1858. "O 
‘Treatise on Electricity and its Applications,’ English edition, vol. 
ili. p. 508*. 
3 (6). The last self-registering instrument to be noticed is that of Herr 
Kreil of Vienna, of which an account appeared in 1855. This in- 
genious and simple instrument can hardly be made intelligible more 
briefly than in the author’s own words, which I translate (with the 
addition of a word or two) from the ‘Sitzungsberichte der Kais. Akad. 
d. Wissensch.’ Band. xv. p. 111, Heft for March 1855 :— 
«A good seismometer is a desideratum still to be devoutly wished for. It 
Fig. 3. 
should not only show the commencement 
of the stronger, but also of the weaker 
shocks, as well as their duration, direction, 
and strength,—a task which is too great for 
a self-registering apparatus. Therefore 
every idea towards the improvement of 
such instruments must be welcome; and 
on this account I venture to bring forward 
the following design (fig. 3). Let de be 
a rod of wood or metal suspended at a, 
which at d is fastened to the elastic 
spring ¢, like the pendulum of a clock, and 
therefore can swing in the plane of this 
spring in a vertical direction. Let ab be 
a second spring upon the first vertical 
one, which permits the bar of the pen- 
dulum, de, to swing in the plane of the 
spring ¢, i.e. at right angles to the former 
vertical plane. The bar de and the 
weight fastened to it can therefore swing 
in every direction, without its being per- 
mitted to turn on its own axis of vertical 
length, and as if there were but a thread 
or thin wire at 6, The cylinder fg hi wy a ae aa oh 
contains clockwork, which obliges it to Whddddiddddddudigy 
turn round upon the bar of the pendulum 
(as its perpendicular axis fixed with reference to rotation) once in 24 hours. 
It is covered with paper or other material, which can be marked on without 
great pressure. It contains on the lower edge the numbers of the hours, 
which can move behind an index m, fastened to the plate kl, which is 
fixed to the axis of the pendulum. Upon a neighbouring pin, o p, is an 
elastic and thin arm of brass, o x, which carries a pencil at ”, which, by 
means of a screw (spring ?), can be pressed against the cylinder and removed 
from it. It is in firm contact with this, and marks upon it an uninterrupted 
line so long as the pendulum remains at rest; if, however, this begins to 
swing, in consequence of the whole system being shaken, this line will be 
broken, and strokes produced which will have a horizontal direction if the 
pendulum swings in the plane of xo, but will be perpendicular and cross- 
ways if swinging in the plane perpendicular to no. The force and length of 
* Since this report was commenced, I have myself had the advantage of seeing this 
instrument, and conversing with its distinguished inventor, as to its principles and construc- 
tion. Prof. Palmieri informed me that it had been arrested by the celebrated shock of 
16th December 1857, and had given indications that he deemed satisfactory. [R.M., May 
1858.] 
