NEWTONIAN REFLECTING TELESCOPE. 193 



tkular subject I have before me namely, this telescope, but you 

 may consider that the same kind of improvement has gone on in 

 everything else ; and yet if we were to observe one thing more than 

 another, we are not so much astonished at the improvements which 

 have been made in this long interval of time, but rather at the tenacity 

 with which old methods utterly unsuited to the purpose for which they 

 were intended have been kept to. Nothing could be more clumsy or 

 ill devised for the object in view than the old quadrants, but they were 

 kept up on the Continent of Europe long after they were given up 

 in England, and long after Pond had superseded them by the mural 

 circle at Greenwich. In the same way it was through an unfortunate 

 mistake of Newton that the reflecting telescope, without those im- 

 provements and the mode of mounting which have made it a very apt 

 and proper instrument at the present day, was kept up in contra- 

 distinction to the refracting telescope. It was supposed that the 

 want of achromatism was hopelessly insuperable. Newton laid down 

 the principle, and others servilely followed it, and thus was delayed 

 the making of large object glasses for the greater part of a century. 

 The tax on glass also, in England at least, was another reason why 

 great object glasses could not be made. It is only within the last few 

 years since the tax has been taken off and that glass has become an 

 article of commerce which could be used freely, that we have been 

 able to reap the full advantage of the scientific improvements which 

 have been made in the construction of glasses, the shortness of focal 

 length, and everything of that sort which renders telescopes of very 

 considerable apertures as manageable as small ones used to be. I 

 make these few rambling and cursory observations with respect to 

 these things to show in some degree the way in which we have got to 

 our present position. The wonder is not so much that, when the 

 human mind is bent on any particular discovery, improvements are 

 so rapid, but that in the preceding century they were so slow. It is to 

 be hoped that, as time goes on, the rate of discovery, rapid as it is at 

 present, will be still further increased. There is no want of genius, 

 no want of scientific means for improvement in material things ; it was 

 want of opportunity and want of interest in the general public which 

 stood in the way. That want of interest has now vanished ; all classes 

 and both sexes, in fact the world at large, take interest now in what 



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