Alfred Harker—Rocks of the ‘ Beagle’? Collection. 101 
, collections which he gathered during that prolonged voyage of 
exploration have therefore no small interest of a historical and 
sentimental kind. It is believed that they possess also a certain 
intrinsic value; imasmuch as an examination of these original 
“specimens, with the advantages conferred by modern petrographical 
methods, may sometimes help towards a better understanding of the 
‘recorded observations. Owing to his choice of plain language in 
“preference to the now antiquated terminology of his time, Darwin is 
seldom obscure to a modern reader; but his characterization of the 
‘igneous rocks which he observed is necessarily crude and vague. Not 
.a few passages may be considerably elucidated by merely indicating 
‘the nature of the rocks which are designated by such old-fashioned 
‘comprehensive names as ‘porphyry,’ ‘ greenstone,’ and ‘basalt.’ In 
general, no more than this will be attempted, at least for those islands 
and districts which have been studied by other geologists with the aid 
of modern appliances. ; 
'. The greater part of the ‘‘ Beagle” collection is now housed in the 
Sedgwick Museum at Cambridge. It includes some 2,000 rock- 
specimens, a certain number being lost or missing, and most of the 
fossils having passed long ago into other hands. Procured often under 
difficult conditions, carried in many cases long distances overland, and 
stowed in a confined space on shipboard, the specimens are for the 
most part not of the size and shape favoured by museum collectors ; 
but they are sufficient to illustrate the rock-masses which they 
represent, and to provide thin slices for microscopical examination. The 
original annotated catalogue, occupying four closely written note- 
-books, is a monument of patient labour. Under each number is 
a condensed description of the rock, as seen by the eye and the lens, 
besides the necessary records of locality and occurrence. On the 
opposite page are additional notes, also made during the voyage, 
‘giving the results of examination with the blow-pipe, goniometer, 
magnet, and acid-bottle. Less commonly there are entries made at 
some later time, sometimes noting an opinion of Henslow or Miller, 
to whom particular questions had been referred. A copy of this 
manuscript list is placed with the collection, and it will be referred to 
‘as the “‘ Catalogue.” 
Santraco, Care Verp Istres. 
Although we shall in general omit petrographical details, some 
exception may be made in the case of rocks which have an interest of 
their own, and have not become generally known from published 
descriptions. Such are the lavas of the Cape Verd Isles, which 
present a considerable range of variety and include some remarkable 
types. ‘The valuable work of Doelter’ does not pretend to com- 
pleteness; and these islands have been so seldom visited by geologists 
that specimens collected seventy years ago may still furnish interesting 
material for study. 
Both on the outward and on the homeward voyage the ‘‘ Beagle” 
_ 1. Doelter: ‘‘ Die Vulcane der Capverden und ihre Producte,’’? Graz, 1882. 
A few rocks collected by Doelter have been described by Fr. Kigel: Tscherm. Min. 
Petr. Mitth. (2), vol. xi (1889), pp. 91-104. . There are also some earlier notes b 
A. Stelzner: Berg. u. Hiitt. Zeit., vol. xxiv, p. 47. a's 
