Elvers during Winter. 137 



or if they are completely empty, — for this circumstance is very 

 necessary, in order to enlighten us as to the place where they 

 originate. 



I am expatiating, however, beyond my plan. I at first 

 merely wished to examine, whether the floating ice was produced 

 at the bottom or the surface of a river. This question can no 

 longer be doubted. The theory is far from being so far ad- 

 vanced. I have pointed out the chasms which it still exhibits. 

 If the recital of these cases can in any way contribute towards 

 their being speedily filled up, I shall be amply recompensed for 

 my trouble. — Annuaire pour VAn 1833. 



ON THE ADVANTAGES OF A SHORT ARC OF VIBRATION FOR 



THE CLOCK PENDULUM. By Mv Edifard Sang. Read 

 before the Society for the Encouragement of the Useful Arts 

 in Scotland, 6th February 1833. 



A LONG intercourse with persons engaged in all the depart- 

 ments of machine-making has brought before me many erroneous 

 ideas. At first I contented myself with exhibiting their fallacy 

 as I met with them, but continued experience has convinced me 

 that a systematic and public exposure of their nature would be 

 of advantage to engine-makers. Following up that conviction, 

 I have projected a series of papers, two of which are already be- 

 fore the Society of Arts. In this, the third one, it is intended 

 to exhibit the impolicy of long sweeps for clock pendulums, 

 and to correct that taste which renders such movements more 

 saleable. 



In these papers, of course, I do not offer my remarks to those 

 who, with laudable zeal, have possessed themselves of a com- 

 plete knowledge of the subjects. Intended for those only whose 

 inattention, or whose want of opportunity, has prevented the ac- 

 quisition of such knowledge, these remarks can hardly claim the 

 notice of the initiated, unless, on the simple ground, that they 

 tend to remove that barrier which separates scientific from prac- 

 tical men. Prevenied from employing the refined and power- 

 ful methods of modern analysis, or even from adverting to the 

 truths presented by the simple sciences, I am reluctantly com- 



