210 



ANNUAL REPORT SMITHSONIAN INSTITUTION, 192 8 



trucks can be made so smooth that its motion does not disturb the 

 telescope in the least. 



If we require special steels or alloys, the assortment we are offered 

 is far larger than we can use. The pyrex glassmaker with his huge 

 tank furnaces stands ready at any moment to let the molten glass 

 flow into the mold, there to cool slowly for months to prevent all 

 strain. Rough-ground and edged, the glass can be raised by means 

 of special lifting apparatus and placed on its bed of counterweighted 

 supports, there to remain until the o[)tician has polished its surface 

 and given it the last touches necessary to converge the star's light 

 into an image smaller in angular size than any ever seen before. 



SKETCH OF A TWENTY-FIVE FOOT EEFLECTlNa TELESCOPE 



F.6. PEASE MOUNT WILSON OBSEBVATOBY 

 PA6ABENA-CAl.lF0KNIA-N0VEM6Eg t ,lfn 



Figure 3. — Sketch of 25-foot reflecting telescope 



In the August, 19i2G, number of these Publications^ was shown a 

 design for a 25-foot reflector planned with a view to making the 

 changes from one attachment to another a matter of only a few 

 moments' time. The observer would stand on a platform just below 

 the opening in the large mirror itself, with practically all of the 

 instruments at hand. The plate holder, spectrographs, photometer, 

 and thermocouple would be mounted each upon a bracket capable of 

 being swung into position with ease. If the night were not good 

 enough for fine nebular photography, five minutes' change would 



* Publications of the Astronomical Society of the Paciflc. 



