196 ANNUAL OF SCIENTIFIC DISCOVERY. 



as -000012, though I do not know how far he could repeat these last with 

 accuracy." 



This is No. 1 of precision. Mr. Kingsley proceeds to No. 2 : 



" But this is rude work compared to the accuracy necessary for the con- 

 struction of the object-glass of a microscope such as Rosse turns out." 



I am sorry to omit the explanation which follows of the ten lenses com- 

 posing such a glass, " each of which must be exact in radius and in surface, 

 and all have their axes coincident; " but it would not be intelligible without 

 the figure by which it is illustrated, so I pass to Mr. Kingsley's No. 3 : 



" I am tolerably familiar," he proceeds, " with the actual grinding and 

 polishing of lenses and specula, and have produced by my own hand some 

 by no means bad optical work, and I have copied no small amount of Tur- 

 ner's work, and I still look with awe at the combined delicacy and precision 

 of his hand; it beats optical work out of sight. In optical work, as in refined 

 drawing, the hand goes bey"ond the eye,* and one has to depend upon the 

 feel; and when one has once learned what a delicate affair touch is, one gets 

 a horror of all coarse work, and is ready to forgive any amount of feebleness 

 sooner than that boldness which is akin to impudence. In optics the dis- 

 tinction is easily seen when the work is put to trial; but here too, as in 

 drawing, it requires an educated eye to tell the difference when the work is 

 only moderately bad ; but with ' bold ' work nothing can be seen but distor- 

 tion and fog, and I heartily wish the same result would follow the same kind 

 of handling in drawing; but here, the boldness cheats the unlearned by 

 looking like the precision of the true man. It is very strange how much 

 better our ears are than our eyes in this country : if an ignorant man were 

 to be 'bold' with a violin, he would not get many admirers, though his 

 boldness Avas far below that of ninety -nine out of a hundred drawings one 

 sees." 



The words which I have italicised in the above extract are those which 

 were surprising to me. I knew that Turner's was as refined as any optical 

 work, but had no idea of its going beyond it. Mr. Kingsley's word " awe," 

 occurring just before, is, however, as I have often felt, precisely the right 

 one. When once we begin at all to understand the work of any truly great 

 executor, such as that of the three great Venetians (Tintoret, Titian, and 

 Veronese), Coreggio, or Turner, the awe of it is something greater than can 

 be felt from the most stupendous natural scenery. For the creation of such 

 a system as a high human intelligence endowed with its ineffably perfect 

 instruments of eye and hand, is a far more appalling manifestation of In- 

 finite Power, than the making either of seas or mountains. 



NEW THEOREMS AND TABLES FOR THE CALCULATION OP EARTH- 

 WORK. 



An interesting mathematical investigation of some problems in the calcu- 

 lation of earthwork, together with tables adapted to such calculations, has 

 been recently communicated to the Pottsville (Pa.) Scientific Association, 



* In case any of your readers should question the use, in drawing, of work too 

 fine for the touches to be individually seen, I quote a sentence from my " Elements 

 of Drawing " ''All fine coloring, like fine drawing, is delicate; so delicate, that if 

 at last you see the color you are putting on, you are putting on too much. You 

 ought to feel a change wrought in the general tone by touches which are individu- 

 ally too pale to be seen." 



