176 LECTURES. " 



at tlie disposal of architecture by the progress of practical science, and 

 particularly by the facility which iron and glass afford in arrange- 

 ments for lighting and ventilation, call for a revision of the practice 

 of former days and for the more extended use of external illumination, 

 or the introduction of ventilated lamps. That phosphorous was an 

 element that might be advantageously introduced for the purpose of 

 artificial illumination, the acid formed by its combustion being con- 

 densed by ammonia^ and returned again by chemical processes in the 

 form of phosphorous. There was no objection to bright lights if the 

 rays from them were sufficiently diffused before they met the eye; but 

 until economy was attained in their construction and management, a 

 double expense was incurred, first in producing them and subsequently 

 in moderating their intensity. 



The physical effect of light upon the constitution was then ad- 

 verted to, and illustrations given from a barrack in St. Petersburgh, 

 where a very marked example was presented of this influence in 

 the prevention of disease. If the rays of light were capable of 

 producing those striking and delicate results that were portrayed by 

 the daguerreotype and the photograph, it would be unreasonable to 

 suppose that their action on the sentient fibres of an organized and 

 living structure would not be still more marked. The influence of 

 light was equally conspicuous on the animal and vegetable kingdom; 

 and the tint given to rooms could be used in some cases of disease as a 

 power in assisting to sooth and subdue an irritable temperament, or 

 in raising, in some degree, the spirits of those that were depressed. 

 He had had, on different occasions, the opportunity of noticing the 

 effect produced in this manner. A room that was of a dead black, 

 and another in which pink and white alternated, were at the extremes 

 of the scale. 



The electric light was the most intense and penetrating artificial 

 light hitherto discovered ; and next to it came the lime ball light. 

 The electric light was accompanied with a perpetual vibration that 

 had not hitherto been overcome ; but 1»he lime ball light could be 

 sustained indefinitely and with great equality, by the use of appro- 

 priate apparatus. The late Sir John Leslie had estimated that the 

 brightest lime ball light had only a one hundred and twenty-third 

 part of the power of an equal amount of solar radiation. 



This lecture was concluded with an account of some experiments he 

 had directed for illuminating the hills at Edinburgh on the occasion 

 of a public festival, when the scenery was made manifest by tons of 

 blue light and other deflagrating mixtures, fired by signals on selected 

 spots on different hills. Nearly a hundred persons were employed on 

 this occasion, and the magnificence and beauty of the effect produced, 

 where isolated landscapes started suddenly into view in the midst of 

 the surrounding darkness, and where the illuminating lights were not 

 seen, confirmed the views he had advocated in reference to the lighting 

 of public buildings. He did not mean to say that naked lights should 

 not be used, and that the light itself should not be visible in all kinds 

 of public buildings. This was not requisite ; nor was it so economical. 

 Lights, also, were pleasing adjuncts in the ball room and on all festive 

 occasions, where their sparkling brilliancy added to the gaiety of the 



