180 Dr.Walchner's Reply to Mr. W. Phillips. 



am reproached by the author, as not being acquainted with 

 the practical use of the reflective goniometer, I feel myself 

 tempted to. reply in a few lines, which you will greatly obhge 

 me by insei'ting in your valuable Journal. 



In determining the inclinations of the planes of the hyalosi- 

 derite, it is true, I have employed the common goniometer; 

 but it was because I had no reflective goniometer at my dis- 

 posal: yet being convinced that any measurement of small 

 crystals afforded by the common goniometer will remain still 

 imperfect, I thought to have prevented any rejiroach on that 

 account, by further observing that my determinations cannot 

 boast of very great accuracy. Some time after the publica- 

 tion of my measurements, Dr.Gustavus Rose * found by means 

 of the reflective goniometer the inclination d — a 139° 16', and 

 observed the plane M in Mr.W. Phillips's figure, which the 

 crystals I possessed had not Therefore the observations of 

 Mr. W. Phillips cannot, it is obvious, pretend to be alto- 

 gether new. 



Mr.W. Phillips allows himself to communicate to the public 

 the unfavourable opinion he entertains of the mineralogists 

 of the continent, whom he pleases to mention as prejudiced 

 against the reflective goniometer. It is indeed singular and 

 astonishing to meet with such a reproach at a time when all 

 measurements are made by means of the instrument of the 

 ingenious Dr. Wollaston ; and it is still more so, considering 

 the many valuable treatises on the improvements of this in- 

 strument, published some years ago in the German journals. 



It may easily be presumed that Mr. W. Phillips, when 

 giving his judgement on foreign mineralogists, was not ac- 

 quainted with those treatises. As they contain the most un- 

 questionable proof of the high esteem the invention of Dr. 

 Wollaston has met with in Germany, I think it incumbent on 

 me, in vindicating the naturalists of my country, to note the 

 authors of some of the most valuable of them : Muncke, 

 TascJicnbiich filr Mincralogie, xiii. 438 ; Studer, Gilbert's 

 Ajinalen, xvi. ; Baumgartner, Gilb. Ann. Ixxi. ; Reysser, iiber 

 gaiauc Messiing der Winkel annalcn Berlin 1826; Rudberg, 

 Vetenskaps Acad. Handlingar 1826. 



I remain. Gentlemen, yours truly, 



Dr. Walchner, 



Carlsruhe, July 16, 1827. Professor of Chemistry. 



* Poggendorff's Aim. iv. 1825. 



XXXV. On 



