868 



likely to believe themselves infallible. Thus the mural quadrant 

 kept its ground, long after its liability to excentricity and change of 

 figure had been recognized. The zenith sector is only now losing 

 its authority ; and it was the invariable practice of this country, at 

 least up to the last twenty years, to rely without examination on the 

 accuracy of divisions. The splendid talents and high authority of 

 Troughton contributed mainly to this state of things, and accordingly 

 as long as it lasted we remained passive ; while in other countries, 

 especially Germany, they were developing new principles of con- 

 struction, and new modes of observation. 



Among these may be named, — 1st, the system of engine division, 

 which possesses the advantage of being capable of progressive im- 

 provement, each circle when examined giving the means of impart- 

 ing greater accuracy to that which shall follow it ; while original 

 division must be liable to an amount of error which will never fall 

 below an assignable amount, depending on causes that cannot always 

 be estimated. 2nd. The principle of casting circles in one piece, and 

 as far as possible avoiding that complication of pieces and screw 

 work so fatal to permanence of condition, which has been the cha- 

 racteristic of English instruments. 3rd. The recurrence to extra- 

 meridional observations, and the use of the collimator in all its forms. 



Notwithstanding the brilliant success with which these changes 

 have rewarded the labours of Bessel and Struve, we have been slow 

 to recognize their value. I have therefore had the greatest pleasure 

 in directing your attention to the important improvements which 

 the Astronomer Royal is effecting in the instrumental apparatus of 

 Greenwich : there the instrument- maker and the engineer are, as they 

 should be, working under the guide of high science ; and even were 

 these instruments, all or any, to be found on longer trial to fall short of 

 their first promise, I should still regard them as important facts. An 

 experiment, when wrought out under the guidance of high intellect 

 and extensive knowledge, is scarcely less precious to science in its 

 failure than in its success : it precludes further trials in an erring 

 direction ; it opens out new paths, and clears away impediments, so 

 that the next step will far more probably be sure. 



The progress of Physiology and Anatomy during the past year has 

 not been marked by any striking discovery, like that of the circula- 

 tion, or of the functions of the different roots of the nerves, or of the 

 vibratile cilia of certain raucous membranes, or of the organization 

 and development of the teeth and other supposed extra-vascular 

 bodies. It has been characterized rather by the comprehensive and 

 philosophic spirit in which the very numerous, and hitherto perhaps 

 too much insulated series of facts have been studied and expanded, 

 through the attention of the able cultivators of those sciences being 

 evidently attracted more to the points of resemblance and analogy 

 than to those of individual and minute differences ; and by the ra- 

 pidly advancing proof of the essential unity of the animal and vege- 

 table divisions of organic nature and of the importance of the ele- 

 mentary cell, or vesicular form of living matter in the development of 

 the various tissues in animals as well as plants. 



