M, Biot m the Length of the Seconds Pendulum. 79 
differ very little from the preceding one ; for, in the 11 series 
already calculated, the one which deviates most from the mean, 
differs from it only ^ths of a millimetre, and the deviation is 
below ^ millimetre for all the rest. As M. Blanc has 
begun the computation of the other series, we shall soon be in 
possession of the result. 
All these observations were made in the Isle of Unst, in the 
house of Mr Thomas Edmonstone. The system of serieses of 
which I have here given the resuk, was observed after the depar- 
ture of Captain Mudge, who had assisted me in the first only, 
having been obliged to leave me on account of ill health. 
Akt. XIV. — Description of an Improved Self-acting Pump. 
By James Huntee, Esq. of Thurston. Communicated by 
the Author. 
The Hungarian Machine, or Chemnitz Fountain, as it is ge- 
nerally called, is one of the few hydraulic engines which has 
been long admired for the ingenuity and simplicity of its con- 
struction. It was originally employed at the mines of Chem- 
nitz to raise water, by means of a small pond, placed at a con- 
siderable height above the surface of the ground at the mine. 
This machine, which required the constant attendance of a 
workman to open and shut the different cocks, by the aid of 
which the effect was produced, has been rendered self-acting, 
by Mr John Whitley Boswell, who has thus added greatly to its 
value. 
Before I was acquainted with Mr Boswell’s improvement up- 
on the Chemnitz Fountain, I had constructed a very simple self- 
acting pump, by means of which water may be raised above the 
original reservoir by the descent of a certain portion of it. 
This pump, which is represented in one of its forms in Fig. 1. of 
■ Plate II. consists of fewer parts, and is less liable to go out of 
order, than the ingenious contrivance of Mr Boswell. 
Description qfthe Improved Self-acting Pump. 
A, is a cistern filled by 
B, a spring. 
