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Ordinary Meeting, February oth, 1878. 
E. W. Binney, F.RS., F.G.S., President, in the Chair. 
Mr. Thomas Harrison, F.C.S., exhibited an apparatus 
devised by Dr. Dixon Mann to obviate the inconvenience 
attending the use of tuning forks in the projection of Lissa- 
jous’ figures on the screen; afterwards he reproduced the 
figures mechanically, by means of his ingenious optical 
adaptation to Tisley’s Harmonograph for showing its move- 
ments on the screen. 
“ On an Improved Method of Projecting Lissajous’ Fi- 
gures on the Screen/’ by J. Dixon Mann, L.K.Q.C.P. 
As is well known, the vibrations of tuning forks when 
used for the production of Lissajous’ figures are kept up 
either by the constant application of the violin bow, or by 
the aid of an electro-magnet ; the former method requiring 
the presence of two assistants, and the latter adding mate- 
rially to the complexity of the apparatus and not unfre- 
quently failing to produce the desired result. The 
difficulty is overcome in the present apparatus by the 
substitution of harmonium reeds for the tuning forks, the 
entire instrument being easily controlled by one operator. 
Proceedings — Lit. & Phil. Soc. — Vol. XVII. — No. 8 — Session 1877-8. 
