The London, Edinburgh and Dublin philosophical magazine and journal of science . ith the pressure in the discharge-tube ; (2) The change in the Lenard-ray current in the samecircumstances ; and (3) The ionizing power of the Lenard rays, i. e. thenumber of ions one Lenard-ray ion produces in travelling-unit distance through a gas at some standard pressure. These experiments will be described in the above order. § 1. The discharge-tube, together with the apparatus usedfor determining the velocity, is shown diagrammatically infig. 1 (p. 30). The cathode rays were produced in a discharge-tubesimil
The London, Edinburgh and Dublin philosophical magazine and journal of science . ith the pressure in the discharge-tube ; (2) The change in the Lenard-ray current in the samecircumstances ; and (3) The ionizing power of the Lenard rays, i. e. thenumber of ions one Lenard-ray ion produces in travelling-unit distance through a gas at some standard pressure. These experiments will be described in the above order. § 1. The discharge-tube, together with the apparatus usedfor determining the velocity, is shown diagrammatically infig. 1 (p. 30). The cathode rays were produced in a discharge-tubesimilar to that originally used by Lenard. A planealuminium disk c served as cathode ; the rod of aluminiumconnected with c was inclosed in a thick-walled glass tube * Communicated by Prof. J. J. Thomson. 30 Mr. J. J. E. Durack on Lenard Bays. to prevent the discharge taking place from the rod, and itwas also found necessary to cover the back of the disk withglass (as shown in the diagram) when intense Lenard rayswere required. An aluminium cylinder a a was used asanode. Tier. The end o£ the discharge-tube facing the cathode wasdrawn down and a brass tube t cemented on with sealing-waxcoated on the outside with a layer of (Munich) soft wax *.An aperture about 1*5 mm. in diameter was bored in the endof the brass tube, the brass being rather thick to preventheating, and the hole bevelled on the inside ; on the outside apiece of aluminium-leaf, 0043 mm. thick, was fastened withsoft wax. This constituted the window W. A water-jacket j j surrounded the tube t to keep the windowcool and so prevent melting of the soft wax. The discharge-tube was kept connected to a Topler pump and McLeodgauge. An outside tube, which, following Lenard, I shall call theobservation-tube, was cemented on to the tube t with sealing-wax; this tube contained the camera 6, was closed at the endwith a rubber stopper D, and connected to a Fleusspump andmanometer. The velocities were found by measuring the magn
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Keywords: ., bookcentury1800, bookdecade1840, booksubjectscience, bookyear1840
