INDUSTRIAL PROGRESS DURING THE YEAR 1875 xliii 



reached on this subject by mathematicians who have studied 

 molecular physics. 



Topler has given an extended illustrated description of 

 the admirable new physical laboratory which has just been 

 erected by the Austrian government at the University at 

 Griitz. 



In Mechanics, Professor Sylvester states that by the study 

 of linkages he has been led to the conception of a new instru- 

 ment, by means of which a figure in the act of being magni- 

 fied or reduced may at the same time be slewed around the 

 centre of similitude. This instrument may be used, there- 

 fore, to transfer a figure from one position on a sheet of 

 drawing-paper to any other position upon it, leaving its form 

 and magnitude unaltered, but its position slewed around 

 through any desired angle. Again, it enables us to apply 

 the principle of angular repetition, to produce designs of com- 

 plicated and captivating symmetry from any simple pattern 

 or form, such as a flower or sprig ; and still it may safely, by 

 practice, be found to place a new and powerful implement in 

 the hands of the engine turner, pattern designer, and the 

 architectural decorator. 



Rood has described in full the important modifications he 

 has made in Zollner's horizontal pendulum, and has given the 

 extraordinarilv delicate measurements he has made with it. 

 The mean probable error of the average result of four sets of 

 observations made with the apparatus is one tenth of a scale- 

 division, corresponding to one thirty-six millionth of an En- 

 glish inch ! Rood purposes to use this remarkable instru- 

 ment for the purpose of studying minute changes, otherwise 

 inappreciable, in the dimensions of solid bodies under various 

 conditions. 



Pfaff has made some experiments upon the plasticity of ice, 

 in order to throw additional light upon glacier motion. In 

 none of the hitherto recorded observations is any mention 

 made of the amount of pressure necessary to change the form 

 of ice, though Moseley observed that to pull apart an ice cyl- 

 inder a weight of five and a half to nine atmospheres was 

 required to the square inch, and to fracture it a pressure of 

 seven and a half to nine atmospheres. Pfaff" has sought to 

 determine the minimum pressure at which ice yields, and has 

 proved that even the slightest pressure is sufficient if it act 



