The London, Edinburgh and Dublin philosophical magazine and journal of science . ching the electroscope. The shieldingfrom this secondary radiation made it impossible to exposethe electroscope to radiation from a large quantity of gas,and made it necessary to place the electroscope some littledistance from the pas the radiation from which was beingstudied. The effects were thus considerably metal box 14 cms. x 10 cms. x 10 cms. was constructed withinlet and outlet tubes for the gases, and with two parchmentwindows, one at the end and the other at the side. In someexperiments the f
The London, Edinburgh and Dublin philosophical magazine and journal of science . ching the electroscope. The shieldingfrom this secondary radiation made it impossible to exposethe electroscope to radiation from a large quantity of gas,and made it necessary to place the electroscope some littledistance from the pas the radiation from which was beingstudied. The effects were thus considerably metal box 14 cms. x 10 cms. x 10 cms. was constructed withinlet and outlet tubes for the gases, and with two parchmentwindows, one at the end and the other at the side. In someexperiments the former was of thin aluminium (*011 cm.).This was for the admission of primary radiation from the secondary radiation passing through the side windowwas studied. 692 Mr. C. G. Barkla on Secondary The arrangement was then as follows:— A bnlb and induction-coil were placed inside a lead-coveredbox M (fig. 3) in one side of which was a rectangular aper-ture A through which a beam of Eontgen rays outside this aperture were lead shutters Sl5 so Fig-. Earth Earth that the width could be varied as desired. Two large leadshutters S2 were placed at a distance of 17 cms. from thisaperture and parallel to the side of the box, so that the widthof a second aperture B was adjustable. The gas chamber described above was placed with its endwindow immediately behind the second screen, with its endface against the two shutters and in such a position that abeam of X-rays passed through the parchment window andthe opposite end of the box while the sides were perfectlyprotected. The electroscope L, which was placed with its thinface opposite and parallel to the side window F, was protectedby lead from radiation which might otherwise have enteredit through its other faces. The thin face was protected fromradiation from all directions except through the window ofthe gas chamber. The primary beam did not fall upon this window, so thatno primary radiation was received by
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Keywords: ., bookcentury1800, bookdecade1840, bookidlondon, booksubjectscience
