306 MR. THOMAS CARRICK ON THE 



furnished by the reflector, as compared with that yielded by 

 the achromatic, however perfectly the latter performed its 

 duty in the important quality of fine definition. 



In conclusion, I could not but feel impressed, while be- 

 holding this fine view of the planet Mars, that I was looking 

 upon a world ! presenting in its remarkable features many 

 close analogies to that of our own, in which respect I am 

 led to consider Mars to be a closer type of the earth, both 

 in its aspect and conditions, than any of the other planets 

 of the solar system. 



XXIV. — On the Wave of High Water ; with Hints towards 

 a New Theory of the Tides. By Thomas Carrick. 



Bead before the Physical and Mathematical Section, April 30th, 1863. 



Professor Airy, in his able treatise on tides and waves, 

 after reviewing in detail the existing causal theories of the 

 tides, passes judgment upon them substantially in the fol- 

 lowing terms : — 



Of the equilibrium-theory of Newton, whilst admitting 

 its great usefulness in some respects, he says that it is one 

 of the most contemptible theories that was ever applied to 

 explain a collection of important physical facts. It is 

 entirely false in principle, and entirely inapplicable in its 

 results. 



Of Laplace's theory he says that, although based upon 

 sounder principles than that of Newton, it fails totally in 

 application, from the impossibility of introducing in it the 

 consideration of the boundaries of the sea, and it gives no 

 assistance in explaining the peculiarities of river or channel 

 tides. 



And of the theory in which tidal waves are supposed to 



