THE CUBA REVIEW 



25 



middle terminal is merely a wire 20 inches 

 in length, held in place by a T connector. 

 The terminals being short offer little re- 

 sistance to the wind. 



The end of the rods should be sharpened 

 to a point and this point heavily painted to 

 preserve it from rust. Rods should be 

 erected every 18 or 20 feet along the ridge 

 of the roof, but the number depends on the 

 cupolas, chimneys or other points on the 

 roof liable to be struck. These should be 

 connected by a short terminal wire to the 

 main conducting wire by a T. The method 

 of running the horizontal wire around these 

 points is shown in figure 3. 



Earth Connections. 



In making earth connections the essential 

 thing is to reach permanently moist earth 

 in the shortest distance from the roof wire. 

 The building in figure 1 has ground con- 

 nections on each side of the building. Two 

 kinds of connections are suggested. One, 

 the ground ends of the vertical wires should 

 be coiled in a spiral having a diameter of 

 about a foot. These spirals should be 

 buried in moist earth under rain spouts or 

 in line of the drip of the roof. This con- 

 struction gives an unbroken run of wire 

 from the ground to the roof of the building. 



A second suggestion is to drive a galvan- 

 ized water pipe, say an inch and a quarter 

 in diameter, into the ground at the foot of 

 the main conductors. Secure a cap for the 

 top of the pipe and bore a hole through it 

 and insert the wire into the iron pipe, fill- 

 ing it with powdered charcoal. The hole 

 in the cap should be large enough to allow 

 water to pass down into the interior of the 

 pipe. 



In figure 1 there are but two ground con- 

 nections, one on each side of the building. 

 A larger building means more vertical wires 

 and more ground connections. A building 

 56 feet long should have at least two con- 

 ductors on each side of the building. 



Buildings With Metallic Roofs. 



A metallic roof properly connected to the 

 earth affords a reasonably good protection. 

 When frame buildings with tin roofs pre- 

 vail there is little destruction by lightning 

 for the down rain spouts conduct the elec- 

 trical discharge to the earth. If an isolated 

 building care should be taken to see that 

 the down rain spouts are surely connected 

 with the ground. It will not do to stop 

 them within a few inches of the ground. 

 The vital points of the connection always to 

 be remembered are to reach permanently 

 moist earth and to secure a perfect metallic 

 joint between the down spout and the earth 

 conductor. If a wire is used it should be 

 flattened out at the end and bolted and 

 soldered to the rain spout. This form of 

 joint should be kept well painted. 



In the case of a building with a metal 

 roof, but no spouts, run a wire conductor 

 from each of the four corners of the roof 

 to the earth, noting the precautions al- 

 ready described. If the building is small 

 as in figure 1, use No. 4 wire. If the 

 building is large enough to require two- 

 vertical wires on each side of the build- 

 ing, and a wire along the ridge of the 

 roof, use No. 3 wire. 



In figure 3 it will be noticed that the 

 bend of the wire is gradual. Likewise in 

 passing over the eaves of a building a 

 goose-neck bend is preferred to a sharp 

 one. The terminal wire for the chimney 

 should be erected at the point shown in 

 the drawing (figure 1). 



FIGURE 3. 



La figura 3 muestra la manera de afianzar los 

 alambres cuando hay en el edificio cupulas, chim- 

 eneas li otras proyecciones. 



If the overhang of the roof is excessive a 

 hole should be bored through it to let the 

 wire pass close to the wall of the building. 



If there are gas pipes in the building, 

 keep the lightning conductors away from 

 them as far as possible, but large masses 

 of metal, such as water pipes, should be 

 connected to the conductors. The water 

 pipes should be in good connection with the 

 ground. 



Joints should be held together mechani- 

 cally and should be frequently examined to 

 see that they are not broken. 



The whole system should receive two 

 coats of aluminum paint and should be re- 

 painted every two years. 



