376 THE CANADIAN NATURALIST. [Vol. viii. 



2nd, magnetite and apatite (unimportant) ; 3rd, magnetite and 

 hematite (important) ; 4th, plumbago (very extensive) ; 5th, 

 phosphate of lime, with iron ores (an important and extensively 

 worked belt) : and then, 6th, Eozoon Canadense, in abundance, 

 with serpentine, chrysotile and veins of baryta and galena. 



You will thus observe that iron ore runs through the series, 

 though most important in one horizon ; that plumbago (with a 

 great deal of pyrites cobaltiferous) is toward the upper por- 

 tion ; while the great body of apatite-bearing rock is at the very 

 summit. 



■%.■%.■%.■%.-%.■%. >£ ^ >£ 



The Huronian and Hastings series of rocks I believe to be 

 simply an altered condition, on their western extension, of the 

 lower portion of my second system • and this alteration com- 

 mences as this portion reaches Hastings county, where you will 

 remember Hunt, Macfarlane and others likened, them to the 

 Huronian, while Sir William thought they more resembled some 

 portions of the Devonian. — Am. Journal. 



Preparations are being made at the Champ de Mars, Paris, 

 for executing Poucault's pendulum experiments on an enlarged 

 scale. His apparatus was suspended in 1851 under the dome of 

 the Pantheon. It was in operation for a long while and re- 

 moved only when the building was transformed into a church 

 after the coup d'etat in 1852. The weight of the pendulum 

 will be 300 kilogrammes, and it will oscillate at the end of an 

 iron wire from 65 to 70 metres long. Thus a special construction 

 will be required for its suspension. The pendulum will be sus- 

 pended above a grooved pipe which will move freely on an axis 

 in its centre. The pendulum in oscillating will displace this 

 pipe, which will remain, like the pendulum itself, fixed in space, 

 in reference to the constellations. Underneath the pendulum 

 will be arranged a large terrestrial globe, from 25 to 30 metres 

 in diameter. This globe, resting on the ground, will necessarily 

 follow with the spectators the movement of the earth. The pipe, 

 on the contrary, supported by a pivot at the extremity of the 

 axis, will carry large indexes, which will appear to be displaced 

 with it. The globe, which will represent the earth, having a 

 considerable volume, the movement of these indexes will be 

 visible ; it will render tangible in some degree to the least atten- 

 tive, the rotation of the planet on its axis. — Nature. 



