Experiments for determining the Length of the Pendulum. 173 
these five sets of keys, equal in grandeur to an orchestra of one 
hundred and fifty performers. 
During the winter season, Messrs. Flight and Robson have 
given, at stated periods, a series of instrumental evening concerts 
. on the instrument; for the conducting of which they have been 
so fortunate as to engage a professor, before not sufficiently 
known, Mr, Thomas Adams, but whose musical abilities are such 
as to rank him in the highest class of his profession. Under his 
direction, and accompanied by four other eminent professors, 
have been performed some of the finest selections of classic 
music from the compositions of Dr. Boyce, Purcell, Bach, 
Handel, Haydn, Mozart, Beethoven, &c. &c. The approba- 
tion with which these performances have been honoured by a 
numerous class of visitors evinces that the English, who have 
hitherto been considered not as a musical people, are perfectly 
capable of appreciating and admiring, to the fullest extent, real 
good music, when placed before them. The highest praise is 
due to the proprietors of the Apollonicon, for thus introducing a 
species of performance that by its superiority will tend to culti- 
vate the rising musical taste ; and I trust that the lovers.of music 
will continue to render that encouragemeut and patronage to the 
instrument, in the next season, which its superior merits are so 
deservingly entitled-to. 
I an, sir, 
Your obliged servant, - 
AN AMATEUR. 
XXVIIL. An Account of Experiments for determining the Length 
of the Pendulum vibrating Seconds in the Latitude of London. 
By Capt. Henry Kater, F.R.S. 
[Continued from p. 100.] 
Of the Apparatus and Methods employed for the Measurement 
of the Distance between the Knife Edges, and for the Com- 
parison of the British Standard Measures of the highest Au- 
thority. 
HE microscopes used for this purpose were made by Mr. 
Thomas, Jones, of Cockspur-street. They are both furnished 
with cross threads of spider’s web, as well as with a single thread 
for the purpose of bisecting a dot if required, and are in other 
respects of a similar construction with those described by Sir 
George Shuckburgh Evelyn, in the Philosophical Transactions 
for 1798, but are more powerful, and the micrometer is capable 
of far greater precision. 
The object-glass of the micrometer microscope is. of one inch 
focus, 
