•3- 



NA TURE 



[June 7, 1883 



making better contact, and allowing a stronger current 

 to flow. At every condensation of the air the membrane 

 moved backward, and the upper end of the lever moved 

 forward, so as to press less strongly than before against 

 the spring, thereby making a less complete contact than 

 before, and by thus partially interrupting the passage of 

 the current, caused the current to flow less freely. The 

 sound-waves which entered the air would in this fashion 

 throw the electric current, which flowed through the point 

 of variable contact, into undulations in strength. Reis 

 himself termed the contact-part of his telephone an 

 interruptor. That it was not intended to operate as an 

 abrupt make and-break arrangement, as some persons 

 have erroneously fancied, is evident ; firstly, because the 

 inventor introduced delicate springs to give a following- 

 contact, and so prevent abrupt breaks from occurring; 

 secondly, because abrupt breaks would have violated the 

 fundamental principle to which he refers in the sentence 

 immediately preceding his description of the instrument 

 shown to the Frankfort Society, namely that of creating 

 tones whose curves were like the undulatory curves im- 

 parted at the transmitting end of the instrument ; thirdly, 

 because (in another article) he described his instrument 

 as opening and closing the circuit in proportion to the 

 sound-wave, which obviously an abrupt "break-and- 

 ma';e " apparatus without a spring-contact could not 

 possibly do. The mechanism which Reis thus invented 

 — and which is substantially alike in all his instruments 

 — might be appropriately described as the combination 

 of a tympanum with an electric current- regulator, the 

 essential principle of the electric current-regulator being 

 the employment of a loose or imperfect contact between 

 the two parts of the conducting system, those parts being 

 so arranged that the vibrations of the tympanum would 

 alter the degree of contact, and thereby vary the resist- 

 ance offered at the point of contact to the passage of the 

 current, and so regulate the strength of the current that it 

 should magnetise and demagnetise the core of a distant 

 electromagnet in a manner corresponding to the undula- 

 tions of the tympanum of the transmitter. 



The particular form of the instrument shown at Frank- 

 fort in 1S61, and described in the Journal, is somewhat 

 different from the " ear." The figure (5) and description 

 are taken from the Journal. 



"In a cube of wood, r stunt w x, there is a conical 

 hole, a, closed at one side by the membrane, b (made of 

 the lesser intestine of the pig), upon the middle of which 

 a little strip of platinum is cemented as a conductor of 

 1 he current. This is united with the binding-screw, ft. 

 From the binding-screw, ;/, there passes likewise a thin 

 strip of metal over [he middle of the membrane, and 

 terminates here in a little platinum wire, which stands at 

 ri^ht angles to the length and breadth of the strip. From 

 the binding-screw, ft, a conducting-wire leads through the 

 b ittery to a distant station." 



In the original instrument there is also an adjusting- 

 s rew to regulate the contact, though this is not shown in 

 1 lie drawing. 



The receiver used to reproduce the sounds transmitted 

 by these telephones is also described in the memoir of 

 Reis. It consisted of a steel needle surrounded by a coil 

 of wire. This was at first set up for the purpose of 

 increasing the sounds by resonance, upon the top of a 

 violin ; later it was mounted upon a pinewood box, to 

 which still later a lid of thin pine was added against which 

 ih : listener could press his ear. The sounds emitted by 

 such a wire during magnetisation and demagnetisation 

 were well known before, but to Reis is due the discovery 

 th it other tones than the natural vibration-tone of the 

 wire could be electrically imposed upon it by the varying 

 magnetising force of the current in the surrounding coil. 

 Reis explained the reproduction of the transmitted 

 sounds by supposing a magnetic attraction between the 

 ;>tims of the steel wire to work synchronously with the 



fluctuations of the current. He later devised a different 

 receiver in which an electromagnet was provided with an 

 elastically mounted armature of iron which it threw into 

 vibrations corresponding to those of the original sound- 

 waves. With this apparatus and a transmitter with a 

 small curved lever like that in the " ear," he was able (see 

 Kuhn's " Handbuch der Angewandten Elektricitatslehre," 

 1866, p. 1021) not only to reproduce melodies with 

 astonishing exactness, and single words as in speaking 

 and reading (less distinctly), but even to transmit the 

 inflexions of the voice expressive of surprise, command, 

 interrogation, &c. 



Considering how far these early researches were carried, 

 it is remarkable that their historic value has been so 

 greatly overlooked. Silvanus P. THOMPSON 



SQUALLS 



T N a short calendar for the present year, issued by Dr. 

 ■^ Gustavus Hinrichs, 1 are two interesting charts of 

 the fronts of squalls passing over Iowa from north-west 

 to south-east. He remarks that the lines between which 

 •5 inch and ro inch of rain fell in one of these squalls on 

 July 31, 1877, gradually diverge as the storm-front rolls 

 down to the south-east, while bending more and more, so 

 as strangely to recall the lines of equal timber in Eastern 

 and Southern Iowa. 



The lines showing the configuration of these squalls 

 are very similar to those showing the shapes of the most 

 extensive European squall-, and the almost complete 

 parallelism between the chart of the squall above 

 alluded to, and those 2 of the Eurydice squall, which 

 traversed England on March 24, 1878, is worthy of the 

 attention of meteorologists. Squalls of this description 

 strictly deserve the name of "arched squalls" (apparently 

 bestowed by English seamen on all squalls which are 

 seen in perspective to rise as arches of cloud above the 

 horizon), for when plotted out upon a chart they are 

 found to be, at the period of their greatest development, 

 scimitar or crescent-shafted, the central portion of the 

 area of squall being in front of the right and left wings, 

 and a chord of the arc so formed being commonly 

 normal, or nearly so, to the isobars existing at the time. 

 It seems probable that the most projecting portion of the 

 line of clouds forming the front of the squall traverses 

 the line of steepest atmospheric gradients, but of this no 

 proof has yet been furnished. The strongest wind is, in 

 any case, commonly experienced in the immediate front 

 of the squall along the line traversed by the focus of the 

 squall, and the greatest precipitation in the rear is also 

 usually experienced along this line. There is one charac- 

 teristic which the crescent-shaped squall shares with the 

 very local squalls common in the temperate latitudes in 

 the rear of a depression, viz. the violent down-rush of cold 

 air experienced under the front of the squall-cloud, fol- 

 lowed by a comparative calm in its wake. In the 

 crescent-shaped squall there is a veering of the lower 

 wind and a backing of the upper wind, sometimes to the 

 extent of about eight points, which is not traceable in 

 the more local squall. In the crescent-shaped squall a 

 sudden increase of atmospheric pressure is experienced 

 at the earth's surface at the time of the strongest rush of 

 wind. This characteristic seems to be shared by the 

 majority of squalls which occur in the Persian Gulf and 

 in Northern India from the north-west, and also by many 

 squalls in the Indian and China seas (which may possibly 

 prove to be of the crescent-shaped type) ; and it is pre- 

 cisely analogous to the rise of barometer frequently 

 noticed at inland localities in the temperate zones during 

 a summer thunderstorm. It is, however, stated that in 



1 " Notes on the Cloud Forms and Climate of Iowa." Dr. G. Hinrichs, 

 Director Iowa Weather Service. 



'Meteorological Magazine, vol. xiii. p. 33; Nautical Magazine, vol. 

 xlvii. 5. 



