CORRESPONDENCE. 95 



in the other puts them down again. His love of truth and fair deal- 

 ing is shown by the following observations : 



Having advertised my objectives not needing correction, in the 

 year 1864 I had a microscoi)e exhibited at our meeting of " Natur- 

 forscher und Aerzte," in Giessen, giving everyone an opportunity to 

 convince himself of the fact— the object-glass was y^th. After the 

 lovers of truth had convinced themselves of the correctness of my 

 statement, in comes Dr. Dippel, bi'inging along with him an object, 

 covered with a i>iece of looking-glass plate of at least three-quarters of 

 a millim. in thickness, through which he knew well enough no Veth in 

 the world could reach, requesting me to put it under the microscoj)e, 

 to try how it would work with various thickness of covering glasses. 

 When I told him that such covers coiild not be used under any lens of 

 high power, he went away declining to make any trial of the lens, and 

 then he threw out his innuendoes without any positive statements. 

 Whether my lenses are capable of doing service, Dr. Schumann 

 has shown. And in spite of the tyro-like brasswork, nearly all our 

 first-class microscopists have either such bad microscopes or object- 

 glasses of my construction, which are not made to look at, but to look 

 through. Hoping you will helj) to right a much-wronged man, 



I am most truly yours, 



B. Hasert. 



[We have pleasure in inserting Herr Hasert's letter. We have 

 not altered his modes of expression, through a desire to maintain the 

 exact character of his remarks. — Ed. ' M. M. J.'] 



The New Powell and Lealand j^th. 



To the Editor of the ' Monthly Microscopical Journal.'' 



BiiisTOL School of Chemistry, December 31, 1875. 



Sir, — In communicating the following notes, I must premise that 

 I have no wish to advocate any particular interest, nor yet to take part 

 in the hot controversy which I regret to see raging round the peaceful 

 instrument which has often given me peace. My aim is solely to 

 endeavour to aid working microscojjists by the results of my own 

 experience. 



In your June issue, Mr. Slack published some remarks on the 

 " New-formula " |^th of Messrs. Powell and Lealand which were very 

 discouraging to those hoping to employ it for general work. Whilst 

 fully admitting its exquisite resolving power on diatom tests, he 

 stated that its working distance was extremely small and its penetra- 

 tion very limited, while it was difficult to use inasmuch as it gave 

 a rapid, almost violent transition from perfect performance to bad 

 performance, or even no performance at all. This report was dis- 

 heartening, coming from such a well-known microscopist ; but how- 

 ever it might have applied to the particular glass examined by 

 Mr. Slack (which I am given to understand was one of the earliest 

 dry ones), it is so singularly inapplicable to my more recent " im- 



