GliOPHYSICAIv R]E;SEARCH — DAY. 179 



tion of this cement, which is now prepared by routine methods, with rather 

 inadequate knowledge of the chemical processes actually involved. 



We have also found further and most interesting relations between the 

 direction and linear force of crystal growth and the physical forces acting 

 upon the growing unit at the time; we have developed some new methods 

 for the optical study of our crystals ; and our high temperature measurements 

 have now reached quite extraordinary refinement. The aggregate error in 

 our pyrometric apparatus is now no greater than o.i° at i,ooo° C. 



The staff of investigators was increased on January i, 1906, by the appoint- 

 ment of Dr. Fred Eugene Wright, formerly of the United States Geological 

 Survey. Before his appointment it was necessary to have the microscopic 

 study of our mineral products undertaken elsewhere. His cooperation has 

 therefore made it possible for us to cover practically the entire ground over 

 which we have worked within our own staff. 



It has not been found necessary during the present year to add materially 

 to the equipment described in the last annual report. 



THE SCIENTIFIC WORK OF THE YEAR. 



The crowded quarters which the laboratory has occupied in what is prac- 

 tically an office building have made it inadvisable to begin any of the 

 systematic work at high pressures which has been contemplated from the 

 beginning of the undertaking. Several pieces of special apparatus have been 

 designed and built for this work, the mounting of which it has been found 

 necessary to postpone until a special laboratory and more favorable condi- 

 tions shall become available. 



The published work of the laboratory during the year 1906 includes twelve 

 papers, all of which have appeared (or will appear before the close of the 

 year) in the scientific journals in the order and under the titles indicated 

 below : 



(i) The phase rule and igneous magmas. Arthur L. Day and E. S. Shepherd. Econ. 

 Geol., I, 286-288. January, 1906. 



A brief criticism of certain sweeping and fundamental assumptions which 

 had been made the subject of a geological discussion under this title by Mr. 

 T. T. Read, in the previous number of Economic Geology. 



(2) Der Isomorphismus und die thermische Eigenschaften der Feldspate. Arthur L. 



Day and E. T. Allen. Zeit. f. phys. Chem. 54, 1-54. January, 1906. 



An extract from Publication No. 31 of the Carnegie Institution, printed in 

 German. 



(3) On wollastonite and pseudo-wollastonite — Polymorphic forms of calcium metasili- 



cate. E. T. Allen, Walter P. White, and Fred Eugene Wright. Amer. Journ. 

 Sci., (4), 21, 88-108. February, 1906. 



Reviewed in last annual report. 



