1 1 g correspondence. 



Mr. Tolles' J^th and ^^^th Objectives. 



To the Editor of the ^Monthly Microstopical JournaV 



Boston, June 23, 1874. 

 Sir, — The paragrai^li on p. 264 of the Journal for June, current, 

 and copied from the Boston ' Journal of Chemistry,' in reference to 

 J^ and -^^ inch objectives is erroneous, in one particular I Jcnow, viz. in 

 implying that only one ^Lth of 165° angle was constructed, whereas 

 three were made simultaneously or carried along together to com- 

 pletion. 



In the next place, it is not likely that any comparison with 



English objectives of like powers or power had been made, and the 



statement implying such comparison was made under misapprehension. 



But reported results of separate trial are available, of course, for 



comparison. 



Yours respectfully, 



EOBT. B, ToLLES. 



Dr. Pigott's (?) Inventions. 



To the Editm- of the ^Monthly Microscopical Journal.^ 



4, Mylne Street, E.G., June 25, 1874. 



Sir, — The invention which Dr. R. Pigott claims as his own in the 

 Journal for this month, has been public property since July, 1870. 

 At that time I read a paper on, and exhibited, an apparatus, at a 

 meeting of the Q. M. C, in every respect but one identical with that 

 described by Dr. Pigott. Moreover, I then expressly stated that the 

 plan in question had been foreshadowed by Mr. Sollitt and others. 



But I think that I am correct in affirming that no one before my- 

 self has ever puhltdy described or used it. The employment of an 

 achromatic objective as a condenser, set ohliquely to the axis of the 

 microscope, at angles varying with the nature of the object to be ex- 

 amined, is what I claim. But I am of opinion that my method of 

 using it is better than that of Dr. Pigott — inasmuch as I added a 

 graduated circle to the carriage of the objective, in order to measure 

 the angles of use, so as to repeat them exactly in future observations. 

 Dr. Pigott may have privately used this apjiaratus before my time, 

 but then it was scarcely possible for those who, like myself, had not 

 the advantage of intimacy with him, to be aware of the fact. More- 

 over, I venture to think that Dr. Pigott does but scanty justice to the 

 labours of others in the same field, when he bestows upon them such 

 faint notice as he has done in my case — even after he had his atten- 

 tion called to them by Mr. Frank Crisj) when his paper was read. 



I am. Sir, yours obediently, 



John Matthews. 



