(69) 
this gave rise to too many difficulties at the time, and it was only 
tried to diminish the variations of temperature by making a second 
wooden case round the clock. *) 
In the meantime the ehronographie method had been generally 
adopted at the observatory for the meridian observations. Now it 
had been shown repeatedly that the introduction of an electrical 
contact in a clock diminishes the regularity of its rate, and on 
the other hand we had found that the comparison of two clocks 
could be effected with extreme accuracy by means of signals given by 
hand *). Accordingly the clock Honwié was not connected with the 
chronograph, but the clock by KNosiich was used for this purpose. 
On the 26th of November 1877 the clock was stopped for a short 
time in order more completely to adjust its beats; since that date 
however it has been going uninterruptedly until August 1898. At 
that time the clock was again dismounted at the occasion offered 
by alterations in the transit-room, and cleaned and overhauled by 
Mr. Honwi, 
In December 1898 the clock was remounted, and this time the former 
plan of removing it from the transit-room was carried out, and it 
was fixed to the pier of the 10 inch refractor. In order better to 
secure a constant temperature, Prof. H. G. van pr SANDE BAKHUYZEN 
resolved to have a niche cut out from this pier in the large hall 
of the observatory, and to place the clock in this niche. 
The clock Honwié N° 17 has now been in its new place for over 
three years. It is still enclosed in two wooden cases, and the niche 
itself is closed by a glass door. We may remark already at this 
place that by this arrangement the aim of excluding rapid variations 
of temperature has been attained in a very perfect manner. 
2. In 1887 Mr. WirrerpiNK investigated for a special purpose the 
rate of the clock Honwü 17 during the period 1886 January to 
1887 July. It then appeared that after reduction for temperature 
and barometer the mean rates for the summer- and the winter- 
half-vears were in very satisfactory agreement, while on the other 
1) At the same time a small mirror was attached to the pendulum-bob, to permit 
more: accurate determinations of the amplitude of oscillation. See: H. G. van pe 
Sanne Baxuuyzen, Verslag van den staat der sterrenwacht te Leiden 1876—1877, 
page 12. 
2) From series of signals given by the two observers Witrerpink and FE. F, 
VAN DE SANDE Baxkuvuyzen immediately after each other, on a great number of 
days, the Mean Error of the result of a series of about 24 signals, (including the 
variation of the constant error during an interval of about a month) is found to 
be © 08.0077, 
