Reseahch Buildings 199 



but instead, a shaft from the basement to the attic on the south side of the main chimney, 

 with doors at each level, serves for handling heavj' apparatus with block and tackle. The 

 space under the sloping roof is, at the apex of the roof, about 4 feet higher than the central 

 attic-space, the roof having been carried up to form the sides around the observation deck. 

 This space is 9 feet 5 inches wide and continuous around the entire building, being lighted 

 by windows in the sides of the observation deck and by the small lookouts under the eaves. 

 As the clear height of this space at the outside wall is 5 feet G inches, it is particularly 

 valuable for storage purposes and for any special work requiring long sights or exceptional 

 freedom from air-currents. This space is plastered with a rough sand brown coat, except 

 for the struck-joint brickwork on the outer walls. 



The observation deck (Fig. 8), 29 by 79 feet, is reached by an iron stairway and a 

 hatchway with sliding top. The floor is of 6 by 9 by 1 inch red vitrified clay tile laid in 

 cement grout over a thoroughly waterproofed reinforced-concrete floor. The sides of the 

 deck are sheathed with 14-ounce copper to the roof-crest line. The ventilating and chimney 

 stacks are 3 feet by 5 feet 2 inches in section and extend 8 feet above the deck, about 8 feet 

 from each end, and have already been used as piers in atmospheric-electric work. 



STANDARDIZING MAGNETIC OBSERVATORY. 



There was no attempt made to provide a non-magnetic testing-room in the main 

 research building. Instead an entirely separate and strictly non-magnetic structure to 

 serve the purposes of a standardizing magnetic observatory has been erected, at a sufficient 

 distance from the main building to be practically free from disturbance. (See Plate 8 

 and Fig. 9.) 



The observatory is to the east of the main building, being over 150 feet distant at its 

 nearest point. The general character of this structure, the design for which was developed 

 by Mr. Fleming, and architecturally adapted by Mr. Wood, is in general harmony with the 

 main building. Its outside dimensions are 28 feet by 58 feet, with a bay on the east side 

 21 feet 6 inches long by 9 feet 6 inches wide, and an entrance with vestibule and porch on the 

 west side, 13 feet 6 inches by 10 feet; the ceiling height throughout is 12 feet. The roof 

 overhangs 4 feet on all sides ; the attic space is used only for ventilation purposes, being pro- 

 vided with open louvres at each end and in each gable. The windows have been made of 

 the sliding-sash pattern rather than the casement, as this type seemed to offer some advan- 

 tages for a building of this character, in which it is necessary to provide blinds that may be 

 closed to protect the instruments from the Sun's glare. The windows are made unusually 

 large to secure the best possible illumination. The considerations involved in the design 

 have been primarily non-magnetic construction, and the placing under one roof of a number 

 of observing piers sufficiently far apart so that several observers, without disturbance, can 

 simultaneously standardize and test their instruments. 



Naturally the observatory is built mainly of wood, this being practically the only 

 non-magnetic building material that can be economically obtained. The foundation walls 

 are of concrete, using Saylor's cement and selected sand and gravel, which, upon careful 

 test, showed practically no magnetic properties. However, in order to guard against a 

 disturbance on account of the mass of concrete used in the foundations, the floor is set 

 considerably above the top of the foundation. All of the metal fastenings, flashing, 

 sashweights, locks, other hardware and truss-tie members are of non-magnetic lead, copper, 

 brass, or bronze. 



The piers, as indicated on the plan of the building in Figure 9, are built of a special 

 non-magnetic, steam-baked brick laid in a mortar of lime, cement, and a selected white 

 non-magnetic sand. The 14 piers are built above the floor level to heights over all of 

 36, 42, 50, and 54 inches. For 9 of the piers, used primarily for field-instrument work, 

 there are provided non-magnetic universal eccentric clamps for securing the instruments 



