Makes one’s heart ache to think about them, save as applicable to living things, coupled with the principles of teaching, and have by this decree they are concentrated by lens, _232_; light, 232, 235, 236, 237. Records, master, 319, 320. Reciprocation, 51. Reed, human, 306; pipes, 301, _302_. Reflecting telescope, 260. Relays, telegraphic, 133, 141. Retina, 247. Retorts, 395. Reversing gear, 62; Allan, 65; Gooch, 65; radial, 66. Rocking bar.