Perfect as this instrument seemed, yet after further years of study and experiment, Sir William Thomson was able, at the close of 1883, to present to the world the Siphon Recorder, greatly improved, because in a very much simpler form. In this form of the instrument, instead of the electro-magnets, he used two bundles of long bar-magnets of square section and made up of square bars of glass-hard steel. The two bundles are supported vertically on a cast-iron socket, and on the upper end of each is fitted a soft iron shoe, so shaped as to concentrate the lines of force and thus produce a strong magnetic field in the space within which the signal-coil is suspended. He made instruments of this kind to work both with and without electrification of the ink. Without electrification the instrument, as shown in Fig. 2, is exceedingly simple and compact, and in this form is capable of doing good work on cables of lengths up to 500 or 600 miles. When constructed for electrification of the ink, as shown in Fig. 3, it is of course available for much longer lengths of cable, but for cables such as the Atlantic cables, the original form of the Siphon Recorder is that still chiefly used. The strongest magnetic field hitherto obtained by permanent magnets (of glass-hard steel) is about 3000 C. G. S. With the electro-magnets of the original form of Siphon Recorder as in ordinary use a magnetic field of about or over 5000 C. G. S. is easily attained. In Fig. 4 is shown a _fac simile_ of part of a message received and recorded by a Siphon Recorder, such as is shown in Fig. 1, from one of the Eastern Telegraph Co.'s Cables of about 830 miles length. [Illustration: FIG. 4.] * * * * * Transcriber's note: Spelling variants where there was no obviously preferred choice were left as is. Since there are numerous quotations in this work, this is partly due to spelling choices of different authors. Variants include: "dispatched" and "despatched;" "embedded" and "imbedded;" "encrusted" and "incrusted;" "hurras" and "hurrahs;" "northeast" and "north-east," and similar hyphenation in directions; "per cent." and "per cent" (inconsistent use of period); "recrossing" and "re-crossing;" "rockbound" and "rock-bound;" "signaled" and "signalled;" "stateroom" and "state-room;" "undercurrent" and "under-current." Removed extra comma after "heart" on page 26: "the heart of a prince." Changed "abunance" to "abundance" on page 167: "too great abundance." Changed "Knigthstown" to "Knightstown" on page 187: "at Knightstown, Valentia." Changed "announcment" to "announcement" on page 189: "this simple announcement." Changed "develope" to "develop" on page 299: "develop the resources." Changed "grip" to "gripe" on page 363, for consistency with spelling throughout: "a fresh gripe." Changed "Hemipheres" to "Hemispheres" on page 381: "the two Hemispheres." Changed "mitror" to "mirror" on page 410: "with the mirror attached."