Mr Ritchie on Improving the Phantasmagoria. 37 



Art. V. — Proposal for Improving the Phantasmagoria. By 

 William Ritchie, A. M., Rector of Tain Academy. In 

 a Letter to the Editor. 



Dear Sir, 



Jl ou are well aware, that, in the common Phantasmagoria, the 

 object becomes brighter and brighter as it diminishes, or as it 

 seems to retire, till, at length, it verges into a luminous point. 

 Now, this is so completely contrary to what takes place in na- 

 ture, that the momentary belief of reality > so forcibly impres- 

 sed on the mind, becomes gradually weaker, and at last total- 

 ly vanishes. To supply this defect, I would, therefore, pro- 

 pose the following altei-ation, which will render the deception 

 much more natural and striking. 



Let a small portable gasometer be procured, capable of 

 holding a sufficient quantity of condensed oil gas. Let a 

 stop-cock, having a small groove, gradually deepening, be 

 adapted to it, so that the quantity of gas escaping to the 

 burner may be increased or diminished at pleasure. By di- 

 minishing the light according to a certain law, the brilliancy 

 of the object will be gradually impaired as it retires, the linea- 

 ments of the figure will become shadowy and obscure, and 

 the phantom itself will at length vanish into thin air. If you 

 consider this notice worthy of a place in your Journal, by in- 

 serting it, you will oblige, Dear Sir, your most obedient and 

 humble servant, William Ritchie. 



Tain Academy, Nov. 15, 1825. 



Art. VI. — Notices of Insects of unusual occurrence which 

 have occasionally appeared in great numbers on Trees, <$fc. 

 By Sir G. S. Mackenzie, Bart., F. R. S. Lond. and 

 Edin. In a Letter to the Editor. 



My Dear Sir, 



The appearance, this season, of an unusual number of aphides, 

 which have done great mischief to almost every tree, as well as 



