Fig. No. 4. Comparator Tent. The portion of the tent shown in the plate; is 70 ft. long on the ridge, constructed of the !>est No. 1 navy canvas. The tent consists of seven sectioi altogether, two sections made of strong unbleached calico not being in position when the photograph was taken. At the near end of tent as show in the plate, the end calico section is 10 ft. long on the ridge, and at the other end 7 ft. long on the lidge, the tent when fully erected being 87 ft. lor on the ridge, and about 100 ft. at the ground-line.

C—lα.