ON NATURAL HISTORY MUSEUMS.
249
minerals which are either of interest to the geologist as rock-consti-
tuents, or of importance to the technologist.
In the mineral department, the technological side would admit
of very extensive development. The fine collections exhibited in
the Museum of Practical Geology in London sufficiently show how
the application of mineral bodies to industrial uses may be efficiently
illustrated.
Such collections would admit of great extension, and the more
extensive they could be made the more interesting would they
become to the visitor. But even a small technological collection
may convey a vast amount of information if the arrangement is
under an intelligent and well-trained head. This is admirably
illustrated in the Technological Gallery of the Crystal Palace.4
Here the resources are comparatively limited, yet, by a judicious
system of arrangement, and by means of full descriptive labels, they
form an extremely neat and instructive collection—a collection,
however, which is too often neglected by the visitor to the Palace,
bent solely on pleasure.
From minerals and their applications, it is an easy step to those
aggregations of minerals which constitute rocks, and thus form the
solid crust of the earth. To recognise with precision the various
kinds of rock met with in the course of geological exploration is by
no means an easy task; and a special study, born of mineralogy and
geology, has latterly grown up under the name of petrology or lithology.
... A knowledge of mineralogy is absolutely necessary, as a
preliminary to the study of petrology ; but it often happens that the
constituent minerals of a rock are so minutely developed, and so
confusedly aggregated together, that the ordinary mineralogist finds
himself unequal to the task of separation and discrimination.
Hence, of late years, the microscope has been placed in the hands
of the petrologist, who has used it with singularly good effect in
unravelling the constitution of the more fine-grained and apparently
compact forms of rock. This young branch of science, which I may
perhaps call "Mineral Histology," should be encouraged in every
possible way ; and it would be well to accompany specimens of
crystalline rocks by enlarged drawings, showing their minute
structure as opened out under the microscope.
4 Since the death of Dr. David Price this collection has been neglected.