I'Hii 
EDINBURGH 
PHILOSOPHICAL JOURNAL. 
Art. of the Invention qf Pendulum Clocks hy 
Christian Huygens By J. H. Van Swinden, Council- 
lor of State, Professor of Philosophy at Amsterdam, &c. 
The measure of time is of the greatest importance to civil 
society, and in many departments of science. An accurate one^ 
capable of measuring its minutest parts, is essentially necessary 
for astronomy. Accordingly, different contrivances for this 
purpose have been of old devised ; such as the clepsydrae of the 
ancients, — -to which were Substituted the motion of sand,-^and 
afterwards clocks, furnished with wheelsj and moved by a weight 
or spring. The latter were materially improved by the intro- 
duction of a balanee^ which regulated to a certain degree the 
nation of the wheels. Still the irregularities to which even the 
best of them were subject, were so great, that the most famous 
astronomers, such as Tycho Brahe and Hevelius, though they 
spared no trouble or expence in their construction, were com- 
* The following is a somewhat abridged translation of a paper read before the 
First Class of the Dutch Institute, and inserted in the Third Volume of their Me- 
moirs. Its chief value for the history of Science, consists in the number of hither- 
to unpublished documents which the author has collected ffom the iiianuscript 
papers relating to Huygehs in the possession of the University of Leyden, of which 
large extracts are appended to the memoir. These are not attempted to be given 
here, but may be consulted by every one, being for the most part written in the 
original French and Latin languages. They are referred to in the translation by the 
words Leyden MSS. Short extracts of them have, however, been occasionally addecl' 
in the notes, or incorporated with the text.— Transi,. 
VOL. VI. NO. 12 . APRIL 1822 . & ' ' ' 
