vainly waiting nearly two years for a better casting, he decided 

 to use this casting, which can be replaced in its mounting by a 

 perfect one, if such shall ever he obtained, and he has proceeded 

 with this work with excellenl results in the Hooker building at 



.Pasadena. 



Mr. Ritchey is very courteous and obliging in imparting 

 information to visitors and I am under obligations to him in be- 

 ing allowed to inspect the entire works and for the details of 

 his proceedings. This casting is now upon the huge machine 

 undergoing its first grinding with the grooved iron plate and 

 carborundum, which is sharper and harder than emery. 



At this writing the center of the parabolic curve has heen 

 ground ahout one inch below the face of the circumference. 

 When completed this point will l.e li 4 inches below the edge, 

 which is finished, and the hack has been polished so that it can 

 he silvered, if experience shall show this desirable, to counter- 

 act unequal expansion and contraction, which may he caused by 

 changes of temperature upon the silvered face and unsilvered 

 hack. The parabolic curve will he figured to 3-1000000 of an 

 inch of perfection and its focus will he 41 2-i! feet. The focus 

 ,,f the 60-inch reflector now in use on Mt. Wilson is only 25 

 feet. For this 100-inch reflector there will he live small mir- 

 rors, which will he used in combination with the Large one. 

 These are cast and await polishing. 



At least eighteen months more, perhaps two years, will he 

 required before this instrument will he ready for use, and 

 with the expense of the proposed buildings, its cost will 

 amount to several hundreds of thousands of dollars. 



With the 60-inch reflector .Mr. Ritchey has taken some 

 most wonderful photographs of nebulae which cannot he seen. 

 even by the 40-inch Yerkes equatorial at Lake Geneva, Wis- 

 consin." These photographs show distinctly the mysterious 

 dark rifts and nehulous stars now in process of evolution to 

 other systems, and the Directors of this Academy will prob- 

 ably he able to make arrangements with Prof. Ritchey to ex- 

 hibit these photographs, illustrating a lecture before the Acad- 

 emy during the coming season. 



The construction of the .Museum Building in Exposition 

 Park is nearly completed, and we expect to lake possession in 

 Augusl or early in September. So soon as the desks, stands. 

 cases ami shelving for our Library shall he in place, our Col- 

 Lections will he rapidly assembled in the several departments 

 and the doors thrown open to all students in the various 

 branches of Science, and to the public. We hope to have ev- 

 erything arranged at the commencement of our work for the 

 next season. 



Jx33£dud*v Onyo [<^U^<. 



