pieces of the edge with his bricklayer's hammer. The 

 final rounding was done with the aid of the iron 

 hoops that had made the mold. Dr. Peate fed steel 

 shot between the edge of the disc and the iron semi- 

 circles. He rotated the disc on the turntable and thus 

 rounded it off. 



After this had been done he commenced the rough 

 grinding. Using the large checkerboard tool, steel 

 shot, and levigated emery Dr. Peate ground out a 

 rough hollow. This took only a few days. George 

 Howard stated that the depth of the concavity was 

 about 5/8 inch and the shape correct to within about 

 1/10,000 inch. The calculated concavity of the mir- 

 ror would be 6/10 inch. Peate evidently used the 

 usual method in polishing the large mirror, that is, 

 he covered the tool face with pitch and used rouge 

 (iron oxide) as the abrasive. This method had been 

 used for many years before this time and is still in use 

 today. 



The figuring, which consists of removing high spots 

 to achieve a truly parabolic contour, probably took 

 the longest time to complete. A mirror must be con- 

 tinually tested as this polishing is being done, and 

 since the polishing warms the glass and distorts its 

 shape, it is necessary to allow a long time for the glass 

 to cool before it can be tested. Peate estimated that 

 polishing and figuring the mirror took 750 hours. ^' 



We do not have a really accurate account of how 

 he tested the mirror. Unfortunately none of the 

 eyewitnesses to these tests had any knowledge of optics 

 or of standard testing procedure. The information 

 of those who had such knowledge is all at least second- 

 hand and sometimes even more remote. J. W. 

 Fecker, successor to Brash ear,-* who was one of a 

 group that examined the mirror in 1923, states that 

 Peate did not use the knife edge test but that he did 

 use a pin with a hole in its head in one of the tests 

 used at that time. 



A variety of different tests and diversions with the 

 mirror have been reported. Dr. Peate would enter- 

 tain visitors in various ways. One of these was to 

 train the mirror on an apple orchard in a valley a 

 few miles away. In another Peate would pull out one 

 of his whiskers and hang it on a fence nearly a quarter 

 of a mile away. Peate himself tells of the time spent 

 in testing the mirror, but does not go into detail 



about the procedure. He does mention a testing 

 table that stood about 75 feet away from the revolving 

 table on which the m.irror rested. He says further 

 that the mirror was tested "in all ways known, in the 

 shop and on a pin and a watch dial a thousand feet 

 distant." Of these only the pin test seems to have 

 been a conventional one.^* 



After the polishing, the mirror was silvered. Said 

 Peate: "It was silvered and tried on the heavens in 

 the starless region under Corvus, and under the very 

 imperfect management of the mirror on telescopic 

 stars, the report was as good as could be expected." ^° 

 Dr. Peate must have spent some time testing it on the 

 stars. The mirror was evidently completed sometime 

 late in summer of 1897, and when Peate was satisfied 

 that it was as perfect as possible, he made arrange- 

 ments to send it to American University. He also 

 designed the shipping case to protect it on the trip to 

 Washington. It is described in the University paper 

 as follows: ^'' 



This consists of a box in which the glass is packed and a 

 wheeled truck in which it is swung. It is swung on its edge 

 by iron bands, \vhich go around it over an iron belt which 

 encircles it. 



After waiting for the case, he encountered a further 

 delay by reason of the fact that the express company 

 had no office at Greenville. However the great glass 

 finally was loaded on the train, and on August 24, 

 1898, it arrived safely at American University. 



Although all parties concerned in this project 

 seemed optimistic, no provision for mounting the 

 mirror had yet been made. The University paper 

 which announced the safe arrival of the glass hoped, 

 at a later date, that — 



some day, we trust before long, a noble and generous 

 giver will appear, who will provide for the proper mount- 

 ing of this mirror and also build a worthy housing. 



This donor was never to appear. Five years later, 

 in announcing the death of Peate, the Courier was 

 still appealing for funds to mount the mirror. Late 

 in 1903 it announced that a gentleman in Pennsylvania 

 would contribute $100,000 to defray the cost of an 

 observatory to house the mirror, but nothing further 

 was ever heard of this gentleman. Earlier, before 

 the mirror had been made, the Reverend H. G. 



23 Preston, p. 142. 



^-i The Brashear Instrument Company, after the death of 

 its founder John Brashear, became the J. W. Fecker Company, 

 Inc. This concern is now a division of the American Optical 

 Company. 



"Preston, pp. 142-143. 



^^ The mirror is no longer silvered. The silver surface was 

 apparently removed during the inspection by the Bureau of 

 Standards in the 1920's. 



2" Preston, p. 144. Various notices were published in the 

 American University Courier in 1898. 



178 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



