286 CARNEGIE INSTITUTION OF WASHINGTON. 



season begins. Professor Schwamb, who has continued to act as our 

 superintendent at Fore River, has done everything in his power to 

 hasten the work, but the pressure of other orders has been responsible 

 for the delay. The work on the smaller parts in our own shop has 

 advanced most satisfactorily, and these will be ready to attach to the 

 mounting as soon as it can be assembled on its pier. The driving- 

 clock, which has been completed and tested, is a highly perfected 

 mechanism, and all of the other work is of the same order of excellence. 



MOUNTAIN TRANSPORTATION. 



Further work on the Mount Wilson road, completed by Mr. Jones 

 last spring, has now given it the width necessary for the transporta- 

 tion of the tube (11 feet in diameter) and other large parts of the 100- 

 inch telescope mounting. During the past spring and summer over 

 650 tons of steel for the dome have been taken to the summit on the 

 1-ton and 3-ton auto-trucks. Some of these pieces were 24 feet long, 

 with a maximum weight of 4| tons. 



CONSTRUCTION ON MOUNT WILSON. 



The work of grinding the rails on which the 100-inch dome rotates 

 was finished last autumn, and soon after the completion of the road 

 in the spring the erection of the dome was begun by Mr. Jones. As 

 the dome is 100 feet in diameter, the problem of handUng the heavy 

 girders was a considerable one, but all difficulties have been overcome, 

 and the dome is now almost completely inclosed. Unless the rains 

 are unusually early, the double sheathing should be finished and the 

 shutter in place this autumn, thus providing safe housing for the 

 mounting as soon as it arrives. 



Other work of the year includes the completion of the 60-foot tower 

 telescope, the construction of a storehouse and cottage at the foot of 

 the mountain road, the erection of a small building adjoining the Pasa- 

 dena office for the 20,000-volt direct-current plant for the Stark effect, 

 and miscellaneous painting and repairs. Some work has also been 

 done on the Smithsonian Observatory buildings. 



MOUNT WILSON POWER-PLANT. 

 Mr. Dowd, who has remained in charge of the power-plant and the 

 cleaning and maintenance of the various telescopes, has also done con- 

 siderable work of other kinds. This includes the construction and 

 installation of new push-button control switches for quick and slow 

 motions, a motor-driven single-speed reversible controller for the 

 elevator, and a small four-plunger pump for the coelostat circulating 

 system of the 150-foot tower telescope; a three-speed reversible con- 

 troller for the motor drive of the 100-inch telescope dome, for use in 

 erection; and a single-speed controller for the power-house. Con- 

 trollers have also been built for the 5-horsepower mirror-elevator motor 

 and the 3-horsepower clock-wind motor of the 100-inch telescope. 



