PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 4:71 



cial laws of electrical action flows necessarily therefrom, to wit : 

 the mutual action of electrical elements, the mutual action of 

 closed circuits, and the action of magnets considered as solmoids- 



Great interest is attached to this paper of Mr. Elliott's from the 

 fact that the author has resorted to quartermoris to aid him in 

 arrivino; at the conclusions stated- 



The calculus of quartermoris was invented by the late Sir Wil- 

 liam Rowan Hamilton, of Dul)lin, and the first publication of them 

 was in 1853. In 1855 it was spoken of by Prof Pierce, of Cam- 

 bridge, as a system of great importance, and likely to be exten- 

 sively used in future mathematical investigations. In 1859, Prof 

 Tait, of Belfast; made use of quartermoris in determining Fres- 

 nel's wave surfaces. 



Among the most important papers presented were those of Dr. 

 T. Sterry Hunt, F. R. S., of Montrotil. The following is a S3'nopsis 

 of that : 



On the Laueentian Limestones and their Mineralogy. 



The author alluded to the existence in the lower Laurentian 

 system of three limestone bands or formations of great but varia- 

 ble thickness, which might fairly be compared with the great lime- 

 stone groups of the North American paleozoic system. In addi- 

 tion to these there is probably a fourth and newer limestone 

 formation belonging to the lower or true Laurentian, besides one 

 or more in the unconfonuable overlying Labrador series or Upper 

 Laurentian. The three limestone formations first named are sepa- 

 rately great masses of gneissic and quartz ore strata, and are inti- 

 mately associated with beds in which silicates of lime and magne- 

 sia prevail, together with graphite and various metallic ores. The 

 minerals associated with these limestones and their accompanying 

 strata were next considered, and it was shown that they occur both 

 disseminated in the beds and filling fissures or veins which traverse 

 the strata. The importance in a geological point of view of these 

 veinstones which from their mode of formation might be named 

 endogenous rocks was insisted upon. They may attain very great 

 dimensions and may include any or all of the mineral species 

 belonging to the adjacent stratification, variously grouped, and 

 sometimes having a banded arrangement parallel to the walls of 

 the vein. Among the characteristic minerals of these veins are 

 calcite, apatite, proxene, hornl)lende, serpentine, chondrodite, 

 orthoclase, scapolite philogopite, quartz garnet, idocrase, cpidote, 



