WRITINGS OF JAMES SMITHSON. 117 



were to issue from the loins of the few who had been 

 spared, races which were to he wicked indeed as those 

 which had preceded them, but which were promised exemp- 

 tion from a like punishment, to have preserved any memento 

 of them would have been useless. 



To a miracle then which swept away all that could recall 

 that day of death when " the windows of heaven were 

 opened " upon mankind, must we refer what no natural 

 means are adequate to explain. 



A LETTER FROM DR. BLACK DESCRIBING A 

 VERY SENSIBLE BALANCE, 



Prom Thomson's Annals of Philosophy, Vol. XXVI ; New Series, Vol. 

 X, 1825, page 52. 



EDINBURGH, September 18, 1790. 



DEAR SIR : I had the pleasure to receive your letter of 

 the 9th. The apparatus I use for weighing small globules 

 of metals, or the like, is as follows : A thin piece of fir 

 wood not thicker than a shilling, and a foot long, -fa of an 

 inch broad in the middle, and }-$ at each end, is divided by 

 transverse lines into 20 parts ; that is, 10 parts on each side 

 of the middle. These are the principal divisions, and each 

 of them is subdivided into halves and quarters. Across 

 the middle is fixed one of the smallest needles I could pro- 

 cure to serve as an axis, and it is fixed in its place by means 

 of a little sealing wax. The numeration of the divisions is 

 from the middle to each end of the beam. The fulcrum is 

 a bit of plate brass, the middle of which lies flat on my 

 table when I use the balance, and the two ends are bent up 

 to a right angle so as to stand upright. These two ends 

 are ground at the same time on a flat hone, that the extreme 



