356 Special Reports 



distribution of electricity by special leads within the building as the investigational work 

 may require. These panel-boards are made of transite ebony asbestos wood 1 inch 

 thick, the panel-board cases being lined with thin asbestos-wood. Provision is made so 

 that the boards may be extended to serve any future additional requirements. All 

 switches, connections, plugs, and other electrical supplies necessary in the installation 

 are strictly non-magnetic. Alternating-circuit plug outlets are provided at 16 points 

 in the laboratory tables mounted along the walls of the building (see Fig. 3). Lighting 

 is provided by six 100-watt nitrogen-filled lamps, mounted on the lower members of 

 three of the roof trusses, and by 40-watt ceiling-fixtures in the entry and porch. Each 

 of these lights has a separate switch in the frame of the north instrument-case. Standard 

 hose-bibb and hose-cock connections for both hot and cold water, ^-inch compressed- 

 air outlets, 2^-inch drain outlets, and ^-inch gas outlets are installed at 8 points in the 

 laboratory tables. The pipe-lines concerned with these outlets and the brass conduits 

 for the electrical connections are carried around the wall of the building below the soap- 

 stone tables. 



The laboratoiy tables for the experimental work consist of soapstone slabs 2 inches 

 thick, all carefully selected to be free of magnetic veins and impurities, and mounted on 

 heavy wooden brackets suitably supported by lag-screws set in the inner concrete wall. 

 They are 25 inches wide. The maximum length of slab is 5 feet, and where the slabs 

 come together they are joined by key slot with flat brass key set in cement. The table 

 tops are 40 inches from the floor. Special soapstone galvanometer shelves 2 inches thick 

 are placed at 10 points (see Fig. 3). They extend through and are built in the inner 6- 

 inch wall; the available shelf space is 13 inches by 13 inches. The tops are 54 inches 

 above the floor. 



The outside dimensions of the building are 28 feet by 53 feet; the inside clear 

 height below the exposed roof trusses is 12 feet, and the height from the lower members 

 of the roof trusses to the ridge of the ceiling is about 9 feet. 



Ventilation is secured by three 20-inch copper ventilators as shown by Plate 8 and 

 Figure 3. Those at the north and south ends of the building connect with 4 ducts running 

 to the 4 corners and opening just below the soapstone laboratory tables, while that at 

 the center opens directly into the building. The ventilators are provided with dampers 

 in order that the amount of ventilation may be regulated, and also with fusible links so 

 that in case of fire they will close automatically. 



The total cost of construction, despite the increased costs arising from non-magnetic 

 requirement for all building material, and including grading and the tunnel connection 

 to the main laboratory, but exclusive of the permanent interior equipment, was $8,500; 

 this is at an average rate of about 30 cents per cubic foot, and compares favorably with 

 prevailing rates for ordinary lumber construction. The grading was an important item 

 of cost, since it was necessary to excavate and grade not only for the building but also 

 for a considerable distance to the south and east to provide a suitably graded roadway. 



The following is a brief summary of the specifications: 



Concrete. All concrete to be one part first-class Portland cement, 2 parts clean, sharp, coarse 

 sand, and 4 parts clean gravel (lJ/-ineh and smaller for foundations and 1-inch and smaller for 

 walls). All reinforcing and tics between walls to be brass wire or brass rod as indicated. Reinforced 

 lintels, sills, and sill courses to be cast in place in wood forms and surfaced and treated as directed. 

 All walls in contact with earth to be smoothly parged ^-inch thick with cement mortar made of 

 one part fresh cement, 10 per cent hydrated lime-paste, and 3 parts of clean "down-river" sand. 



Waterproofing. Floor and exterior walls below grade as shown to be waterproofed with 4 

 layers felt and pitch, allowing G inches lap on every joint. A "waster" is to be placed to keep 

 extension from floor clean and dry until the wall waterproofing is attached. 



Plaster. First coat one part approved prepared plaster to not more than 2 parts down-river 

 sand; rough sand finish to be made to 3 <j-inch grounds. 



