554 



H. M. Bernard — Developing Trilohites. 



led, very naturally, to the sand-blast. A visit to the "London Sand- 

 blast Works " (58a, Gray's Inn Eoad) gave some promise. The pro- 

 prietor was kind enough to express interest in the idea, and showed 

 me blocks of granite which had been treated with the sand-blast, 

 and in which the harder elements stood out in good relief. A very 

 short application of one of the sand-blasts belonging to the Works 

 to the under-surface of a Trilobite from the soft Wenlock cleared 

 away a large portion of the matrix, and revealed a small area of the 

 under-surface of the carapace completely cleaned. In this specimen 

 there was no trace of any under membrane having been cut through, 

 and the carapace was probably the last remnant of a cast skin. 



I then applied to Mr. W. I. Last, the keeper of the Machinery 

 Division of the South Kensington Museum, for advice and assistance. 

 He suggested several methods by which a constant stream of sand 

 might be obtained, very kindly allowing me to make use of the air 



Eeproduction of drawing (on greatly reduced scale) to show Sand-blast Apparatus 

 for developing fossils, invented by W. I. Last, Esq. (Keeper of the Machinery 

 Division), Science and Art Museum, South Kensington. 



pressure (about 61bs to the square inch) by means of which the 

 beautiful series of model engines in his charge are kept in motion 

 or set working by the visitor on pressing a button. I take this 

 opportunity of thanking Mr. Last very sincerely for the friendly 

 assistance he rendered, for whatever is of value in this paper, viz. 

 the description of the apparatus, is entirely due to him. 



The sand was first thrown up from the bottom of a deep funnel 

 by the air current rising in its base, always falling back again to 



