66 Froceedings of the Boyal Society 
and he pleased himself by thinking that nothing hut the ocean 
separated him in a right line from Norway. Leaving Portohello 
in May 1839, he spent part of three months in his old favourite 
resort, the Isle of Arran. Here he occupied himself with much 
diligence and zeal in surveying accurately the granitic and trappean 
formations of the island. The results were presented to the Koyal 
Society of Edinburgh, in April 1840, in an elaborate paper, which 
embraces a minute tabular description of no less than 149 individual 
trap dykes in the north-eastern part of the island alone, besides 
giving indications of many more. It was an occupation well suited 
to M. Necker’s state of health, affording constant, yet moderate 
occupation of mind, and attraction out of doors, with the advan- 
tages of a temperate climate, and removal from any interruption, 
or anxiety. The wonderful patience and conscientious ability 
with which this labour was executed is worthy of all commenda- 
tion ; and the really astonishing nature of the phenomena which 
it chronicles with so much minuteness, exempts it from the sus- 
picion of being a useless or puerile employment. So close a survey 
introduced M. Necker to many singular min eralogical and geological 
peculiarities previously overlooked ; and having myself since gone 
over much of the ground with his memoir in my hand, I can testify 
to its wonderful fidelity. It is impossible to foresee how important 
this catalogue of dykes may one day prove to the future dynamical 
geologist.* 
We have an interesting chronicle of Necker’s life at this time, 
in a series of letters to his mother, which were printed soon after 
in the Bihliotheque Universelle de Geneve . They commence at 
Portohello in February 1839, and they unfortunately terminate in 
September. These letters, now buried in a large periodical work, 
are charming in themselves, and give a delightful picture of the 
writer’s capacity for intellectual enjoyment. He always presented 
to his mother the gayer side of his impressions. The little traits of 
* In this paper (Trans. Roy. Soc. Ed., vol. xiv.), Necker refers with much 
interest and satisfaction to his discovery of an outbreak of granite to the north 
of the head of Grlencloy, quite detached from the granitic nucleus of Goatfell. 
Jameson had already noted syenite near this locality. I am not sure whether 
Necker recollected having cited Jameson’s earlier observation in his own Voy- 
age en Ecosse, tom. ii, p. 31, 
t Tom. XXV., xxvi., for 1839 and 1840. 
