132 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



with each bar, the results of which agree with each other far 

 within the limiting probable errors. Hulsse's Inaugural Dis- 

 sertation ,\ 81 3. 



PECULIARITIES OF ORGAN-PIPES. 



Hermann Smith, the well-known constructor of organs, writ- 

 ing on the variability of the node in organ-pipes, states that 

 this is as yet an unrecognized phase in acoustics. From the 

 time of Savart it has been known that the nodal division of 

 the open organ-pipe does not take place at the exact half of 

 the length, and that the half nearest the embouchure is the 

 shortest of these divisions. The position of the node is, per- 

 haps, the most significant fact that presents itself to the at- 

 tention of the investigator, whether student or teacher. The 

 actual extent of the disparity between the "unequal halves" 

 of the pipe can be ascertained, and is found to be subject to 

 laws as definite as are found in other dynamical problems. 

 If a standard open diapason pipe be made for some designed 

 pitch, whatever that pitch may be, it may safely be predicted 

 that the pipe will stand considerably short of the full theoret- 

 ical length. It ought to be about one eighth less, while for 

 the vox-angelica pipes the length of the pipe is about one 

 twelfth less than that which theory demands. Unless this 

 peculiarity of organ-pipes is properly understood and allowed 

 for, great errors arise in all determinations of the velocity of 

 sound in various gases. Hermann Smith's conclusion is that 

 in an organ-pipe there are three different velocities speeding 

 at different rates and concurring in every vibration, and es- 

 sential to the synchronic time of its note. 12 A, IX., 302. 



REFRACTION OF SOUND BY THE ATMOSPHERE. 



Professor Reynolds, of Manchester, has communicated to 

 the Royal Society a paper looking to the explanation of many 

 of the so-called abnormal phenomena of sound, and particu- 

 larly the results of Professor Tyndall's recent observations on 

 the audibility of fog-signals. Professor Reynolds states that 

 the effect of wind on sound is due to the lifting: of the sound 

 from the ground, and not to its destruction, as is generally 

 supposed ; the lifting of the sound being the result of a refrac- 

 tion due to the different velocities with which the air moves 

 at the ground, and at a small elevation above it. Experi- 



