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of Edinburgh, Session 1878 - 79 . 
elucidation of geological problems gradually drew observers away 
from the study of minerals. Consequently, as palaeontology in- 
creased, mineralogy waned among us. To such an extent was the 
study of minerals neglected, that geologists even of high reputation 
could not distinguish many ordinary varieties. But as a knowledge 
of rocks presupposes an acquaintance more or less extensive with 
minerals, the neglect of mineralogy reacted most disadvantageously 
on that domain of geology which deals with the composition and 
structure of rocks. The nomenclature of the rocks of Britain sank 
into a state of confusion from which it is how only beginning to 
recover. To you, Professor Heddle, belongs the merit of having 
almost alone upheld the mineralogical reputation of your native 
country during these long years of depression. You have devoted 
your life to the study, and have made more analyses of minerals 
than any other observer. You have not contented yourself with 
determining their composition and their names; you have gone 
into every parish in the more mountainous regions, have searched 
them out in their native localities, and by this means have studied 
their geological relations, heaping up evidence from which to reason 
regarding their origin and history. After thirty years of continuous 
work you have communicated the results of your labours to this 
Society. For the first two of these papers, “ On the Rhombohedral 
Carbonates,” and “ Oh the Felspars,” in which you have greatly 
extended our knowledge of pseudomorphic change among minerals, 
enunciating a law of the shrinkage so frequently resulting there- 
from, the Society proposes now to express its gratitude to you. The 
value of your papers is undoubted. Through the kindness of Mr 
Milne Home I have been favoured with the sight of letters addressed 
to you by four eminent mineralogists — Dana, of America ; Rammels- 
berg, of Berlin ; Szabo, of Buda-Pesth ; and King, of Queen’s 
College, Galway. Szabo states that the notice of Professor Heddle’s 
paper on the Feldspars which appeared in Groth’s “ Zeitschrift fur 
Mineralogie,” greatly interests him, and makes him desirous of 
placing himself in direct communication with the author. Dana 
says, “ I have read your paper on the Feldspars, in the ‘ Transac- 
tions 5 of the Royal Society of Edinburgh, with great satisfaction. 
Your thorough method of work leads towards important results of 
great geological as well as mineralogical value.” I have the satis- 
