The pitch of the tone excited at C in the rod E E was in the apparatus at my disposal _h_; its strength not very great and its clang snarly, similar to that of a lightly sounding reed-whistle, somewhat like that of a child’s wooden trumpet. The cuticle lying about the heart of the smaller and even the larger mammals (from calves, &c.) makes the best membranes. Goldbeater’s-skins reproduce only the deeper tones. The cover of the sounding-box appeared in my apparatus superfluous, and indeed the tone was somewhat stronger without the cover. 1. In experiments with the telephone, one must look closely as to whether the ends of the platinum strip is still fastened to the membrane, and one must, if necessary, press upon the membrane. If the strip will no longer stick, heat a knife-blade, touch a small piece of sealing wax with it, and carry thus the melted sealing-wax to the under side of the round end of the platinum-strip, _n s_. Then press it immediately on the membrane, _m m_. Ph. Reis showed his apparatus in very primitive form for the first time in October, 1861, to the Physical Society at Frankfort-on-the-Main; on July 4th, 1863, before the same society, he showed the form represented in Fig. 33. This time he experimented upon a distance of 300 feet. Professor Boettger brought the apparatus before the Naturforscher-Versammlung at Stettin (1863) in the section for Physics. [=16.=] HESSLER’S ‘TEXT-BOOK OF TECHNICAL PHYSICS,’ vol. i. p. 648. [Next in chronological order comes a notice of the Telephone in Hessler’s ‘Lehrbuch der technischen Physik,’ edited by Prof. Pisko, and published at Vienna in 1866. The brief account given in this work adds nothing to the accounts previously given, and is evidently written by some person ignorant of Reis’s own work, for beside omitting all mention of the transmission of speech by the instrument, or of its being constructed upon the model of the human ear, the writer appears not even to know how to spell Reis’s name,[37] and speaks of him as “Reuss.”] [=17.=] KUHN’S ‘HANDBOOK OF APPLIED ELECTRICITY,’ (‘Handbuch der Angewandten Elektricitätslehre,’ von Carl Kuhn), being vol. xx. of Karsten’s ‘Universal Encyclopædia of Physics’ (Karsten’s ‘Allgemeine Encyclopädie der Physik’).