May 2, 1902.] 



SCIENCE. 



695 



operations used in the analytical treatment 

 of physical problems. The inherent phys- 

 ical meaning of each step in the treatment 

 should be made evident, and the general 

 nature of the result of each step should be 

 capable of prediction; this may not always 

 be possible, but it is rather more common 

 than not, to avoid such interpretations. The 

 paper dealt with these points as illustrated 

 in the study of heat conduction (or in 

 cabling), and pointed out the importance 

 of that subject for its pedagogical value 

 in mathematical physics. Beginning with 

 the solution for the periodic distribution 

 of temperature about a point, the solutions 

 for other problems were built up, each step 

 in the analysis being first discussed as to 

 its physical interpretation, and the relation- 

 ships of the various solutions brought out. 

 In this way was developed the meaning of 

 many of the common operations involved, 

 the possibility of their being solutions, and 

 finally the interpretation of a Fourier's 

 integral. Among other things, careful 

 drawings were exhibited of the curves for 

 temperature and current for the more im- 

 portant equations. 



Professor M. I. Ptjpin, of Columbia 

 University, New York, in a paper on 'The 

 Law of Magnetic Hysteresis, ' presented an 

 account of a mathematical and experi- 

 mental research upon the magnetic prop- 

 erties of iron which resulted in the dis- 

 covery of a new law in magnetism. This 

 law can be stated as follows: 



' ' The heat generated per unit volume of 

 iron during a cycle of magnetization is 

 proportional to the cube of magnetic in- 

 tensity. ' ' 



This law holds true within the first of 

 the three well-known intervals of magneti- 

 zation. It was discovered by determining 

 accurately the resistance of the magnetiz- 

 ing helix, employing vibratory magnetizing 

 forces of about 1,000 periods per second, 

 and then separating the various compo- 



nents of this resistance by means of mathe- 

 matical analysis. 



This investigation is an extension of the 

 researches of Professor Ewing of Cam- 

 bridge University, England, and of Lord 

 Rayleigh, employing a new and very much 

 more sensitive method. Its results have a 

 very important practical bearing in the 

 manufacture of inductance coils. From 

 its purely scientific aspect the new law de- 

 rives its principal interest from the fact 

 that it will materially assist in the formu- 

 lation of the physical theory of magnetism. 



Professor W. K. Brooks, of Baltimore,, 

 presented a one-minute paper on the sub- 

 ject 'Is Scientific Naturalism Fatalism?' 

 It is impossible to fairly report this paper, 

 already admirably condensed, without pre- 

 senting it in its entirety. It may be said, 

 however, that, basing his opinion on well- 

 known views of Hume and Berkeley, the 

 author maintained that certainty in the 

 natural world does not imply necessity in 

 the agent. 



Professor Brooks also presented a paper, 

 illustrated by drawings and models, on 

 'Dichotoma, a New Genus of Hydroid 

 Jelly-fish,' found in the Bahamas, which 

 shows many resemblances to a fossil form 

 described by Walcott from the Lower 

 Cambrian. 



Professor Henry Kraemer^ of Phila- 

 delphia, in a paper 'On the Continuity of 

 Protoplasm, ' which was illustrated by lan- 

 tern slides, said that a starch grain con- 

 sists of alternate layers of colloidal and 

 crystalloidal substances, and that the col- 

 loidal layers are the ones which take up 

 the various aniline dyes, as gentian violet, 

 eosin, safranin, etc. The various clefts and 

 fissures produced in the grains behave to- 

 ward staining reagents much like the 

 colloidal layers, and they are probably the 

 tracts or channels through which liquids 

 are distributed throughout the grain. The 

 author has observed that by the use of 



