1030 



SCIENCE. 



[N. S. Vol. XI. Iv^o. 287. 



Oue is not surprised at such confusion of mean- 

 iugs in the productions of men who appear from 

 time to time with crude and hazj' schemes for 

 correcting or overthrowing all existing systems 

 of science or philosophy, and who make profes- 

 sors weary by their importunities, but one does 

 not look for it in an honored seat of learning. 

 To find it there makes one wonder whether 

 Helmholtz is unknown, or Maxwell has lived 

 in vain. 



Although mechanics as the oldest of sciences 

 has been chosen for these illustrations it is 

 likely that every other branch of science can 

 show similar perversions. We have even 

 known the ' parallels of longitude ' to be re- 

 feri-ed to in all seriousness, but as that was not 

 uttered by a scientific man it is rather to be 

 smiled at than criticized. 



D. W. Heeing. 



CORRECTION. 



In Xo. 277 of Science, I stated that the 

 MgClj solution used in my experiments on arti- 

 ficial parthenogenesis was a 20/8?i solution. I 

 have since found that the assistant who made 

 the Mg-solution used and who has left the 

 laboratory must have made a mistake as the 

 solution contained only about 120 g. of MgCL 

 in a liter. This does not affect my results, but 

 might be an obstacle to the successful repetition 

 of my experiments by others. 



Jacques Loeb. 



Chicago, June 8. 1900. 



NOTES ON ELECTRICAL ENGINEERING. 

 submarine telephony. 



If waves were sent along a string stretched 

 under water the effect of the water would be to 

 damp the motion of the string causing the waves 

 to become more and more attenuated as they 

 travel along the string, and to distort the waves 

 so that a wave initially complicated in shape 

 would be smoothed and spread out more and 

 more as it travels along the string. 



Assuming the damping or frictional force of 

 the water on the string at a point to be strictly 

 proportional to the sidewise velocity of the 

 string at that point, it can be shown that there 

 is a certain relation between the tension of the 

 string and its weight per unit length for which 



the attenuation of a wave is a minimum and 

 for which a wave is not distorted as it travels 

 along the string. 



A submarine cable for telegraphy behaves in 

 a manner entirely analogous to a string stretched 

 through a viscous fluid as described above. 

 Electrical impulses acting at one end of the 

 cable produce electrical waves which travel 

 along the conductor of the cable. The elec- 

 trical resistance of the conductor is analogous 

 to the frictional resistance of the water on the 

 string, the self-inductance of the conductor is 

 analogous to the weight of the string and the 

 inductive capacity of the gutta-percha insula- 

 tion is analogous to the tension on the string. 



There is a certain relation between resistance 

 of conductor, self- inductance of conductor, and 

 inductive capacity of the gutta-percha covering 

 for which electrical waves suffer minimum at- 

 tenuation and no distortion as they travel 

 along the cable. Oliver Heaviside first called, 

 attention to this condition for the distortionless 

 circuit, as it is called and Dr. M. I. Pupin, in a 

 paper read before the American Physical So- 

 ciety in December, showed that the distortion- 

 less condition can be realized practically by 

 distributed inductance that is by connecting 

 small coils of wire at intervals along a cable or 

 land line. 



The practical importance of the distortion- 

 less circuit is great inasmuch as such a circuit 

 would greatly extend the possible speed of 

 ocean telegraphy and perhaps even make ocean 

 telephony possible. 



The limit of speed of ocean telegraphy is set 

 mainly by the distortion of the electrical im- 

 pulses which pass along the cable. This distor- 

 tion causes the impulses at the receiving end 

 to overlap each other greatly. 



The limitation of long distance telephony is 

 set in part by the attenuation of the electrical 

 waves and in part by the distortion of the 

 waves. The first makes it difficult to produce 

 an audible effect at the distant receiver and 

 the second so changes the character of the 

 waves that the sound in the distant receiver 

 becomes more or less indistinct or inarticulate, 

 consonant sounds are especially liable to be- 

 come confused in this way. 



W. S. F. 



