Chem istry and Phys ics. 153 



and of deserts is believed to be connected with thin pellicles or 

 films of air, or of gases thence derived, deposited and condensed 

 upon the surface of the sand-grains during gradual evaporation 

 after wetting by the sens, lakes, or by rains. By virtue of these 

 films the sand-grains become separated by elastic cushions of 

 condensed gases, capable of considerable vibration, and whose 

 thickness has been approximately determined. The extent of the 

 vibration and the volume and pitch of the sound thereby pro- 

 duced, after any quick disturbance of the sand, is also found to be 

 largely dependent upon the forms, structures and surfaces of the 

 sand grains, and especially upon their purity or freedom from 

 fine silt or dust. Though the environment of the sand on beaches 

 and in the desert differs greatly as respects moisture, this above 

 theory is regarded applicable to both. Water is not wholly 

 lacking even in the desert to aid in the chemical cleansing 

 of the sand grains, and the powerful winds accomplish the work 

 of sorting and winnowing done by the waves elsewhere. The 

 fineness of the grains at the Bell Slopes makes the displacement 

 of a very large amount of sand necessary lor the production of 

 sound, while the coarser particles on the beaches yield a resonance 

 on a smaller provocation. The pitch of the musical notes pro- 

 duced on sea beaches is directly proportional to the mass of sand 

 moved, the greater the mass the lower the tones; on the Bell 

 Slopes in the desert the large mass moved, yields a very deep 

 note. — Amer. Assoc Adv. Science, vol. xxxviii. 



3. Electro ma f/netic effect of Convection. — F. Himstedt has 

 repeated Rowland's experiments upon this subject and concludes 

 that electric convection can produce electromagnetic effects. 

 Rowland's results have been questioned by certain observers, 

 among them, by Lecher (Rep. d. Phys., xx, p. 151, 1884). Him- 

 stedt believes that Lecher's apparatus was not sufficiently sensi- 

 tive to obtain the phenomena. During the progress of his work, 

 Himstedt discovered that ebonite shows traces of magnetism and 

 therefore he used glass discs. The method was the same as that 

 employed by Rowland. Two glass discs, rubbed with graphite, 

 and strongly charged were set in revolution, one on each side of 

 an astatic combination. The speed of the discs was from 60 to 

 1 70 revolutions per second. In general Himstedt confirms Row- 

 land's work. He does not however confirm Rowland's observa- 

 tion that a difference is called forth by changing the direction of 

 rotation. Xo difference could be observed. — Ann. der Physik 

 und Chemie, 1889, No. 12, pp. 560-573. j. t. 



4. MechcDticcd equivalent of Light. — II. O. Tumlirz states 

 his results as follows: A surface of 1 square centimeter placed at 

 a distance of 1 meter from the planes of an Amylacetate lamp — 

 in such a way that the normal to the surface is horizontal and 

 passes through the middle of the plane — receives per second a 

 quantity of light which expressed in units of work is 



15 # 15 {cm 2 f/ sec -2 ) 



1 sec 



