Optical Curiosities of Literature. 231 



impossibility, but suppositions cost nothing — suppose a high-power 

 glass could be made to reach the centres of the pillulse, what be- 

 comes of the immersion ? For to command the aperture, the glass 

 must work dry. And if, changing it yet again, he designs another 

 remedy by applying what he calls the " flowed-iu-liquid," what be- 

 comes of the aperture ? for as soon as the liquid is " flowed-in " the 

 aperture is flowed out, and the inexorable 82^ is upon him again. 



The rest is in keeping. The best thing is where he quotes the 

 experiment with the water-tank against itself, A ^Vth in the tank 

 showed 100'^; and this being admitted he cannot for his life think 

 why it does not end the case ; for, as with touching simplicity he 

 observes, 100° is surely larger than 82^. So it seems that after 

 having had just half a year to think over the experiment, IMr. Tolles 

 has never found out that in this case the object is in water as well 

 as the objective; and that the same law which admits the higher 

 limit for water, necessitates for the very same reason the lower limit 

 for balsam. 



In his new curves which form additional designs he is equally 

 at fault. His diagrams are falsely drawn, and the hues do not give 

 the refractions they are indicated as giving — a grave fault at any 

 time in a professional workman, but altogether inexcusable where 

 the very point at issue turns on the magnitude of the angles in 

 question. Into this I need not enter, however, in detail ; for though 

 in one sense public property, it is in the first place the business of 

 Mr. Wenham, who is the most competent to show its merits. Whether 

 he will choose to do so is of course another question. Having 

 twice set Mr. Tolles on his feet, he may not feel himself called on 

 to repeat the process indefinitely. In any case I should not, for 

 the present at least, have noticed it, but for the accidental coincidence 

 of its coming in connection with the paper just written ; supplying 

 as it does a new and unexpected illustration of the extent to which 

 skill of a high order in manual work may coexist with absolute 

 ignorance of the principles on which the work depends. 



