ADDRESS. 



liit 



the division of labour, whilst the attention which each department receives, 

 and the harmony with which the plan has hitherto worked, afford the best 

 guarantee of its wisdom and proof of its success. 



In the early history of Astronomy, how vague and unsatisactory were the 

 wild theories and conjectures which supplied the place of demonstrated 

 physical truths and carefully observed laws ! How immeasurably small, 

 what a very speck does man appear, with all the wonders of his invention, 

 when contrasted with the mighty works of the Creator; and how imperfect 

 is our apprehension, even in the highest fligiits of poetic imagination, of the 

 boundless depths of space I These reflections naturally suggest themselves 

 in the contemplation of the works of an Almighty Power, and impress the 

 mind with a reverential awe for the great Author of our existence. 



The great revolution which laid the foundation of modern Astronomy, 

 and which, indeed, marks the birth of modern physical science, is chiefly 

 due to three or four distinguished philosophers. Tycho Brahe, by his 

 system of accurate measurement of the positions of the heavenly bodies, 

 Copernicus, by his theory of the solar system, Galileo, by the application of 

 the telescope, and Kepler, by the discovery of the laws of the planetary 

 motions, all assisted in advancing, by prodigious strides, towards a true 

 knowledge of the constitution of the universe. It remained for Newton to 

 introduce, at a later period, the idea of an attraction varying directly as the 

 mass, and inversely as the square of the distance, and thus to reduce celes- 

 tial phenomena to the greatest simplicity, by comprehending them under a 

 single law. Without tracing the details of the history of this science, we 

 may notice that in more recent times astronomical discoveries have been 

 closely connected with high mechanical skill in the construction of instru- 

 ments of precision. The telescope has enormously increased the catalogue 

 of the fixed stars, or those " landmarks of the universe," as Sir John Herschel 

 terms them, " which never deceive the astronomer, navigator, or surveyor." 

 The number of known planets and asteroids has also been greatly enlarged. 

 The discovery of Uranus resulted immediately from the perfection attained 

 by Sir William Herschel in the construction of his telescope. More recently, 

 the structure of the nebulae has been unfolded through the application to 

 their study of the colossal telescope of Lord Rosse. In all these directions 

 much has been done both by our present distinguished Astronomer Royal 

 and also by amateur observers in private observatories, all of whom, with 

 Mr. Lassell at their head, are making rapid advances in this department of 

 physical science. 



Our knowledge of the physical constitution of the central body of our 

 system seems likely, at the present time, to be much increased. The spots 

 on the sun's disk were noticed by Galileo and his contemporaries, and enabled 

 them to ascertain the time of its rotation and the inclination of its axis. 

 They also correctly inferred, from their appearance, the existence of a lumi- 

 nous envelope, in which funnel-shaped depressions revealed a solid and dark 

 nucleus. Just a century ago, Alexander Wilson indicated the presence of a 

 second and less luminous envelope beneath the outer stratum, and his dis- 

 covery was confirmed by Sir William Herschel, who was led to assume the 

 presence of a double stratum of clouds, the upper intensely luminous, the 

 lower grey, and forming the penumbra of the spots. Observations during 

 eclipses have rendered probable the supposition of a third and outermost stra- 

 tum of imperfect transparency enclosing concentrically the other envelopes. 

 Still more recently,the remarkable discoveries of Kirchhoff andBunsen require 

 us to believe that a solid or liquid photosphere is seen through an atmosphere 

 containing iron, sodium, lithium, and other metals in a vaporous condition. 



