190 PLYMOUTH INSTITUTION. 



the mode of preventing them by ventilation &c. ; this part of the 

 subject he exemplified by a neat little model of a house in which 

 he suffered gas to escape, and then exploded it ; but it was here 

 found that even, with a design to do mischief, it was very dif- 

 ficult to guess the exact proportions of gas and air necessary for 

 this, in consequence of which, the little edifice withstood admi- 

 rably well its violent internal shocks and commotions, and in 

 short remained uninjured. 



August 14th. — Mr. Swain's Lecture on Insanity. 



The highly interesting paper, on the above important subject, 

 was read to the Society during the Winter session ; an ab- 

 stract of which may be found at page 34, Vol. 3rd, of the 

 ** Museum ; " it was this evening substituted for one on Natural 

 Philosophy. 



August 21st. — Mr. Hearder's Lecture on Flame. 



The lecturer commenced by explaining the difference which 

 exists between the phenomena of combustion, produced by dense 

 and solid matter, and those produced by the action of aeriform 

 bodies on each other. In the latter case the combustion is perfect, 

 and the temperature highest. Having examined the various 

 causes winch modify the nature and appearance of Flame, he pro- 

 ceeded to show the practical advantai^es which mankind had de- 

 rived from this peculiar property, which combustion possesses 

 of existing in a gaseous form ; and exemplified the nature and 

 manufacture of oil gas, by means of neat and simple apparatus. 

 He showed the relative combustibility of different bodies, and 

 explained the principle of that peculiar modification discovered 

 by Sir Humphry Davy, and called by him invisible combustion. 

 He showed the action of spongy platinum upon hydrogen gas; 

 together with its application as a mode of producing instantaneous 

 light ; and, after having explained the nature and action of wire 

 gauze in extinguishing flame, he concluded, by showing the in- 

 tense heat produced by the combustion of the mixed gases in the 

 oxy-hydrogen blowpipe. 



August 28th. — Mr. Lancaster's Lecture on Astronomy, 

 On this evening, the lecturer confined his remarks wholly to 

 the astronomy of the Earth ; commencing with a statement of its 

 dimensions; he brought forward the proofs of its particular form, 

 noted the refractive properties of its atmosphere, and the annual 

 and diurnal motions; spoke of the solar and sidereal year and 

 day, of the cause of leap year and the change of the style ; he 

 ilescribed with much care the elliptical form of its orbit, accounted 

 for the change of the seasons, and concluded by noticing more 

 particularly the different lengths of day and night, and the du- 

 ration of twilight. 



