wrillcn him a iiimsI uanii Idler nf reci >miiK'n<hilii iii and coinnicn- 

 (lation. 



It is a jilcasure to present that article in this nuUetin, and no 

 (.Ioul)l it will prove of absorhinj^' interest to all our members. 



Lookinij^ to the future, we hope to induce Mr. Ford .\. Car- 

 penter, the accomplished Director at Los Angeles of the Weather 

 Bureau Station, to i^ive u> a i):ii)er ui)i>n the subject <if whicli lie is 

 so profound an exponent. 



E.\RLY in the year l')06. John Dag^^ett Hooker, Vice-Presi- 

 dent of this Academy, proposed to the Carnegie Institution of 

 Washington, the construction of a one hundred-inch reflecting 

 telescope at the Mount Wilson Solar Observatory, and he ofifered 

 to donate fifty thou&and dollars for the expense of a glass disk of 

 that dimension in case the Institution would furnish the necessary 

 mounting and a suitably domed housing. 



His offer was accepted, and in September. 1906, he ordered the 

 disk from the French Plate Glass Company, having its works at 

 St. Gobain. France. 



During two years many castings w^ere had. and finally, in 

 December, 1908, a disk, nearly 14 inches thick, 102 inches in diam- 

 eter and weighing more than five tons, was received at Pasadena, 

 but it was found to be imperfect in many respects, as it lacked 

 homogeneity necessary for equable expansion and contraction in 

 that it contained millions of air bubbles and striae. 



]\[r. Hooker sent Prof. G. -W. Ritchey, Superintendent of 

 Instrument Construction, to France for the purpose of instituting 

 a mode for a perfect casting, and. not content with this additional 

 expense, he caused to be erected in Pasadena, a noble fire-proof 

 building in wdiich the grinding, polishing and figuring of the disk, 

 might be done, and for this labor he supplied all the necessary 

 appliances and tools at a cost of many thousands of dollars. 



After a .stay of several months in St. Gobain. ]\Ir. Ritchey be- 

 came satisfied that the w^orks were unable to cast a disk more free 

 from flaws than the one forwarded, and. upon his return to Pasa- 

 dena, he gave the glass a more careful examination. He discov- 

 ered that the imperfection nearest the parabolic reflecting curve, 

 when polished and figured, would be about a quarter of an inch 

 below its surface, so he decided to proceed with the completion of 

 the disk, which could be removed from its mounting in case a 

 perfect casting should be obtained at a future day. 



A more particular account of yir. Hooker's activities in this 

 regard, was given in our Bulletins of Januarv. 1909, and Tulv, 

 1911. 



The first enunciation of this great project, appeared in our 



