158 HISTORY OF PHYSICAL ASTRONOMY. 



ted upon Laplace's theory, and thus it was never fairly brought to the 

 test. 



It is, perhaps, remarkable, considering all the experience which as- 

 tronomy had furnished, that men should have expected to reach the 

 completion of this branch of science by improving the mathematical 

 theory, without, at the same time, ascertaining the laws of the facts. 

 In all other departments of astronomy, as, for instance, in the cases of 

 the moon and the planets, the leading features of the phenomena had 

 been made out empirically, before the theory explained them. The 

 course which analogy would have recommended for the cultivation of 

 our knowledge of the tides, would have been, to ascertain, by an anal- 

 ysis of long series of observations, the effect of changes in the time of 

 transit, parallax, and declination of the moon, and thus to obtain the 

 laws of phenomena ; and then proceed to investigate the laws of cau- 

 sation. 



Though this was not the course followed by mathematical theorists, 

 it was really pursued by those who practically calculated Tide-tables ; 

 and the application of knowledge to the useful purposes of life being 

 thus separated from the promotion of the theory, was naturally treated 

 as a gainful property, and preserved by secrecy. Art, in this instance, 

 having cast off her legitimate subordination to Science, or rather, be- 

 ing deprived of the guidance which it was the duty of Science to afford, 

 resumed her ancient practices of exclusiveuess and mystery. Liv- 

 erpool, London, and other places, had their Tide-tables, constructed 

 by undivulged methods, which methods, in some instances at least, 

 were handed down from father to son for several generations as a fam- 

 ily possession ; and the publication of new Tables, accompanied by a 

 statement of the mode of calculation, was resented as an infringement 

 of the rights of property. 



The mode in which these secret methods were invented, was that 

 which we have pointed out ; the analysis of a considerable series of 

 observations. Probably the best example of this was afforded by the 

 Liverpool Tide-tables. These were deduced by a clergyman named 

 Holden, from observations made at that port by a harbor-master of the 

 name of Hutchinson ; who was led, by a love of such pursuits, to ob- 

 serve the tides carefully for above twenty years, day and night. 

 Holden's Tables, founded on four years of these observations, were 

 remarkably accurate. 



At length men of science began to perceive that such calculations 

 were part of their business; and that they were called upon, as the 



