Il2 On the Alii hide and Azimuth Instrument, 



laro-c instruments' on tliis principle. With regard to the other 

 limit, I woiilcl remark that as to instruments smaller than one 

 one loot diameter, however useful they may be for surveying 

 of land and other inferior purposes, I should consider them 

 for astronomy as little better than playthings. 



As to its form and general appearance, R is, of all the in- 

 struments subservient to astronomy and geodesy, the most 

 uncoutli and unsightly. The whole of the effective parts are 

 placed on one side of its single supporting pillar ; and on the 

 other a weioht, almost equal to the instrument, is placed for 

 the purpose of keeping it in equilibrio. But ugliness is not the 

 worst thin<y that attends this unavoidable combination ; for it 

 renders the instrument top-heavy, tottering, and weak. In 

 these respects A is certainly very much superior. The whole 

 of its fabric is regular and self-balanced ; the upper circle, be- 

 ino- supported like a transit on tv*o columns, is thus rendered 

 finn and steady. Respecting sightliness, I diink die man of 

 taste would, in the diftiirent forms it has appeared under, pro- 

 nounce it agreeable, I dare not say beautiful ; and here I may 

 be allowed to remark, that the art of instrument making, as a 

 matter of taste, is far behind many others. In this country, 

 indeed, at the beginning of the art, instruments were adorned 

 with the flourishes of the engraver, chaser, and carver (now 

 long out of fashion): but these are not the beauties which I 

 mean; those of uniformity of figure, and just proportions are 

 alone wliat I have in view ; and I cannot for a moment think 

 that diese are at all inconsistent with either strength or ac- 

 cm'acy. 



Through the whole of tliis paper every reader will have seen 

 that I am an advocate for A, and I ha^e made no endeavour 

 to conceal it : yet, if I liave said moi'e for it than it deserves, 

 or given to R less than its due, it is a thing I am quite un- 

 conscious of. Having now finished what I had to say by way 

 of comparison, a concluding remark or two only remain to be 

 added. One of our artists, through a course of twenty-five 

 years, has made the repeating circle under various forms; 

 some of them lla^e repeated horizontal angles, others vertical 

 angles, and more of them have done both ; which last have 

 obtained the name of repeating theodolites. All these are of 

 a firmer fabric than that treated of in this communication ; yet 

 after having, as he fancies, gone through all the changes of 

 repeating instruments, he owns that he has never satisfied him- 

 self in a single instance. I am informed that some of our in- 

 strument-makers are at this time endeavouring to improve the 

 repeating circle; but I would submit it to their serious consi- 

 deration, whether their time and talents might not be better 



employed 



