292 Fusion- Structures in Meteorites. 



the one instance where Zirkel in his work (Plate XVI, Fig. 1) 

 pietnres a form approaching to some extent those here nuder 

 consideration, he designates it as " Krystalliten-tiggregation," 

 i. e., aggregation of cr3'stallites. 



After mature delibei'ation, I decided to name these forma- 

 tions "Fusion-stjuctnres ;" and I trust that the observations 

 detailed further on will justify my choice of an appellation. 



After these inti'uductory remarks, it will be in place to present 

 a brief and general outline of the work done, the material used, 

 and the methods emj^loyed, and then to take up more in detail 

 such points as may prove of special interest, finally giving the 

 results and conclusions attained. 



The investigation embraced the examination of meteorites, 

 lava, rhyolite, tufaceous trachyte and basalt. For the material 

 of which my meteorite-sections were prepared, I am indebted 

 to Drs. C. F. Chandler, J. S. Newberry, T. Egleston, Jr., and 

 C. U. Shepard ; and my acknowledgments are also due Mr. 

 Hague, of the U. S. Geological Survey, for the kindness with 

 which he placed a valuable collection of rock-sections at my 

 disposal. 



The method of work followed, was to examine each section 

 carefull}^ with a comparatively low power, 75 diameters, to note 

 any fusion-structure observed, and to study this attentively with 

 higher powers, ranging from 150 to 800 diameters — in one in- 

 stance even as high as 1,500 diameters; 300 diameters, how- 

 ever, was the one usually employed. Then was noted the 

 behavior of the structure with regard to polarized light, and 

 after this, generally, a rough sketch was made of the structure, 

 and with slide-number attached, placed in a book kept for the 

 purpose. From this book were afterwards chosen the most de- 

 sirable forms; the respective slides placed under the microscope, 

 and the figures on the plates were then drawn free-hand directly 

 from the glass. 



The meteorite sections, of which there were 31 in all, repre- 

 sent seventeen different specimens — care being taken to obtain, 

 wherever possible, both longitudinal and transverse cuts. 



Following is a list of these meteorites, recording where known, 

 the place and date of their fall, and in some cases giving their 

 composition, with name of the analyst. 



