NATURE 



[September 3, 1914 



effectiveness of an appeal to facts against the 

 verbalism which springs from uncritical accept- 

 ance of the abstract laws of thought." 



Natural Sines to every Second of Arc, and Eight 

 places of Decimals. Computed by E. Gifford. 

 (Manchester: Abel Heywood and Son, 1914.) 

 Pp- 543- Price 155. 

 Any practical means of assisting the computer is 

 to be welcomed, and this volume of natural sines 

 to every second of arc, and to eight places of deci- 

 mals, will be sure to have a considerable practical 

 value, even to those who use machines. The sines 

 to 10" are those from the "Opus Palatinum of 

 Rheticus " (published 1596); the sines to 1" 

 were interpolated by the Thomas calculating 

 machine being copied to ten places. The table is 

 arranged like Chambers' log tables, the figures to 

 the right of the seconds being prefixed to each of 

 the sets in the same horizontal line, except when 

 the sets are dotted, 

 when the first four 

 digits are taken from 

 the line below. Con- 

 sidering the laborious 

 nature of, and the 

 accuracy required in 

 the construction of 

 these tables, the com- 

 piler is to be heartily 

 congratulated on the 

 successful completion 

 of the task. 



THE TYPE-READ- 

 ING OPTOPHONE. 

 ANY instrument de- 

 signed for trans- 

 lating optica] into 

 acoustic effects, or 

 light into sound, and 

 thus to some extent 

 substituting the ear 

 for the eye, may be 

 appropriately termed 

 an "optophone." The 



intermediate link is either heat or electric 

 current, smd in view of the fact that a 

 current of a few thousandths of a microampere 

 is audible in the best modern telephones (if inter- 

 mittent), one would naturally use an electrical 

 rather than a thermal link. This is done in the 

 various forms of "optophone" devised by the 

 author since the Optical Convention of 1912. 



The latest of these, described before the Royal 

 Society on May 28, and shown at the conver- 

 sazione of the society on June 16, is designed with 

 the object of enabling blind persons to "read" 

 ordinary letterpress by means of the ear. The 

 accompanying illustration of the optical arrange- 

 ment is reproduced from the Royal Society paper 

 by permission of the council. 



An optical system throws the image of a glow- 

 ing Nernst filament upon the printed paper, laid 

 face downwards on a suitably perforated desk. 



NO. 2340, VOL. 94] 



This image is broken up into a series of seven or 

 eight luminous dots, flashing with different musi- 

 cal frequencies, by means of a rotating siren disc 

 placed immediately in front of the Nernst fila- 

 ment. Some light-sensitive preparation, prefei'- 

 ably of selenium, is placed close to the type so as 

 to receive whatever light is diffusely reflected by 

 it. The size of the image is made to fit the size 

 of type to be read, and a sensitive telephone is 

 put in series with the selenium and a battery, or 

 with one of S. G. Brown's telephone relays. 



It has been found possible to obtain a "read- 

 able " sound from type of the ordinary newspaper 

 size. The straight black stem of a letter produces 

 silence, and a curved letter, such as S, produces 

 in its passage a set of gradually changing note*? 

 which are characteristic of the letter, and cannot 

 be mistaken even after only a few minutes' prac- 

 tice. To learn the entire alphabet in this way 

 should be a matter of a few weeks or months, 



Type-reading optophone. N, Nernst lamp ; S, rotating siren disc ; P, portrait lens, throwing image of line of Jnter- 

 mittenl dot* on the printed matter placed face downwards at H ; Se, selenium preparation receiving diffusely 



reflected light. 



but the amount of practice required will vary ver} 

 greatly from one person to another, as only i 

 " musical " ear can readily detect the omission ol 

 certain notes from a given chord. Given an ade^ 

 quate alignment and line-changing mechanism 

 there is no reason why, with sufficient practice 

 ear-reading should not be almost as rapid as th( 

 ordinary reading at sight. 



The choice of type is, of course, unlimited 

 There is no arbitrary element in the determina 

 tion of the sounds required to represent the vari 

 ous letters, as each type will automatically pro 

 duce its own characteristic sounds. With con 

 siderable practice, a blind person, thus trainee 

 to allocate certain notes to certain positions 

 should be able to construct " instinctively " i 

 visual (or tactile) image of any new or unfamiliai 

 letterpress type at the first hearing. 



E. E. FouRxiER d'Albe. 



