Memoir of the late Francis Baily, Esq.^ F.R.S., SfC. 47 



cause,) this sentiment, so far from diminishing, seemed to 

 grow upon him, till he regarded its welfare and interests as 

 identical with his own. I shall reserve a more distinct state- 

 ment of our obligations to him for a more advanced period of 

 this notice ; but in a narrative of his life it becomes impossible 

 from this epoch to separate the Astronomical Society/ from 

 astronomical sciefice, in our estimate of his views and motives, 

 or to avoid noticing the large and increasing devotion to its 

 concerns of his time and thoughts. To the Transactions of 

 the new Society he became, as might be expected, a frequent 

 and copious contributor. In the interval between the first 

 establishment of the Society and the year 1825 (the reason 

 for this limit will presently be seen), he contributed five papers, 

 viz. : " On the Meridian Adjustment of the Transit Instru- 

 ment ;" "On the Determination of Time by Altitudes near the 

 Prime Vertical;" "On the Solar Eclipse of September 20, 

 1820;" "On the Mercurial Compensation Pendulum ;" and 

 " On the Determination of Longitudes by Moon-culminating 

 Stars." The two first- mentioned of these turn on somewhat 

 elementary points of astronomical observation, and contain 

 tables, and suggest facilities which he had found useful in his 

 own practice. The eclipse was observed by him at Kentish 

 Town, where, not being annular, he must have felt severely 

 the sacrifice, imposed probably by the calls of business, of the 

 opportunity of witnessing, by a short continental trip, a phse- 

 nomenon which had engaged so much of his thoughts. His 

 paper on the mercurial pendulum, though practical in its ob- 

 ject, was of a much more elaborate kind than anything which 

 had previously emanated from him, with exception of his 

 memoir on the eclipse of Thales. It contains a minute and 

 excellent view of the whole subject of this most useful com- 

 pensation, is prefaced [more suo) with a clear synoptic view 

 of the then actual state of the subject, and goes into the whole 

 subject of the expansion of the materials, the formulae for de- 

 termining with more precision than heretofore the proportional 

 length of the mercurial column, and the mode of adjustment 

 both for rate and compensation. This paper must certainly 

 be regarded as a very valuable one, and an astronomer can 

 liardly be said thoroughly to understand his clock who does 

 not possess it. The object of the paper on moon-culminating 

 stars is to recommend, facilitate and render general, that most 

 useful and widely available method of determining the longi- 

 tude on land. 



About this period also Mr. Baily began, and thenceforward 

 continued, to be a frequent contributor to the Philosophical 

 Magazine, published by Messrs. Tilloch and Taylor, of ar- 



