240 CARNEGIE INSTITUTION OF WASHINGTON. 



With the completion of this pier the concrete construction work 

 will be finished, with the exception of the floor at the ground-level. 

 This will probably be delayed until after the erection of the building 

 and dome and the heavier parts of the telescope mounting. 



In addition to the work upon the 100-inch-telescope foundations, 

 a considerable amount of general construction work has been com- 

 pleted. Two small wooden cottages have been erected, one of three 

 rooms for Mr. Jones, the superintendent of construction, located near 

 the 100-inch telescope site, and one of four rooms for the assistant 

 engineer, near the power-house. 



The need for additional space at the power-house has been felt 

 strongly during the past year. Accordingly the building has recently 

 been enlarged by an extension to the north to a distance of about 15 

 feet. This provides more space for the machine-shop, a small room 

 for a blacksmith's forge, and a considerable amount of storage space 

 for stock materials and tools. This construction, like that of the 

 remainder of the building, is of reinforced concrete with a roof of steel. 



The principal other piece of construction work during the summer 

 has been a remodeling of the interior of the laboratory. With the 

 increase in the number of observers, the need of more office room 

 has been most evident. By means of a simple change in the location 

 of the chemical room the entire southern end of the building has been 

 made available for this purpose, and with the construction of a few 

 partition walls, six additional small working-rooms have been added. 



Other minor pieces of construction and repair work during the 

 summer have included the laying of the remainder of the electric- 

 power wires in underground conduits ; the construction of a concrete 

 muffling pit for the two gas engines of the power-house ; the repairing 

 of the laboratory roof; the construction of several short sections of 

 new road on the mountain, and a considerable amount of brush- 

 cutting with a view to the reduction of fire risks. 



The Observatory has also built and installed for the Smithsonian 

 Institution the mounting for a concave mirror of 75 feet focal length 

 and for an auxiliary mirror to be used on the tower on Mount Wilson. 

 The instrument will be employed for observations of the radiation at 

 different portions of the sun's disk. 



