Lovering and Bond on Magnetic Observations at Cambridge. 3 
projections are given of only those parts of the building which are 
devoted to the purposes of an observatory; they were built express- 
ly for this object and are attached to the northwest and southwest 
corners of the house in which the observers reside ; one room of this 
house which is used for an observer’s room is represented in the 
plate by K. is the projection of the dome erected on the top of 
the house, and the rectangle is the opening through the floor by 
which it is entered. This dome has a revolving roof of panel work 
and plate glass with a vertical section which can be brought into 
any azimuth required by the observation. is the place of the as- 
tronomical clock.* It has been thought inexpedient to carry the 
clock into the transit room where it would be exposed to great 
changes of temperature. For this and other reasons it is kept in a 
fixed position in a room where the temperature is nearly uniform 
throughout the day and night, and at all seasons. The observations 
are made directly with a chronometer which is compared with the 
clock as often as is necessary. This practice has recommended 
itself from long trial as convenient and safe. G represents the place 
of the barometers. ‘The observatory is liberally furnished in this 
respect, having one standard barometer by Cary and two barom- 
eters by W. & S. Jones. Besides these, a beautiful standard ba- 
rometer made by I. Newman has just been received and has been 
placed between the windows on the south side of the same room. 
As this barometer is after the model of those used at the other mag- 
netic stations and has been compared directly with the standard 
barometer of the Royal Society which was made by the same artist 
on the same principle, it may be regarded as the best standard in this 
country. The following are the results of the comparison : 
Royal Society Standard 29.506 in. Royal Society Standard 28.604 in. 
Cambridge Standard 29.504 Cambridge Standard 28.600 
* This clock was made by Parkinson and Frodsham. 
