88 CAPTAIN SABINE ON THE DIFFERENCE IN THE VIBRATIONS 
the rate of an invariable pendulum between the Royal Observatory and 
Mr. Browne’s house in London ; the pendulum vibrating quicker in Greenwich 
than in London. 
The retardation computed for the difference in latitude between the two sta- 
tions is 0.15 of a vibration per diem, and for their difference in elevation being 
about 50 feet and employing Dr. Young’s co-efficient of .6, is 0.12 of a vibration 
per diem. The sum of the two computed retardations is 0.27 ; which added 
to the acceleration 0.48 shown by the experiments, makes altogether 0.75 of a 
vibration per diem ; by which amount the result of experiment differs from 
what would have been anticipated, supposing that no previous experience 
had existed of the occurrence of such anomalies. 
With regard to the fact, of the existence of this irregularity between Green- 
wich and London, it is one which admits of easy verification by persons who 
may be disposed to repeat the experiments : the stations are convenient and 
close at home ; and the magnitude of the irregularity is such as to preclude 
uncertainty, since with proper precautions, it is not difficult to determine the 
relative rates of an invariable pendulum to nearly jth of the present irregu- 
larity. 
With regard to its cause, — having already expressed the opinion that I had 
been led to form on the occurrence in my former pendulum experiments, of 
what I believe to have been irregularities of a similar nature, — it is unnecessary 
now to repeat that opinion ; and having since seen no occasion to alter it, on 
the contrary much to confirm it, I gladly leave the discussion to others whose 
opinions are entitled to more weight. 
