The Optical Magic Lantern Journal (October 1902)

6 THE OPTICAL macis LANTERN JOURANL mark from members who used oil lamps and projected on a large screen. It is impossible without fuller particulars to compare the illumination given by the oxy-hydrogen with that given by the oil lamps, but in the case of the three members using Stocks 4 wick oil lamp some estimate of the comparative illumination on the screen may be formed. Assuming the lhght emitted by the lamp to be the same, in one case it was spread over 49 sq. ft., in another over 16 sq. ft., undin my own case over about Tdsq. ft. So the brightness of my light on the screen was nearly I1 times as great as that of the second member’ s, and nearly "33 times as great as that of first mentioned member. No wonder then that the estimate of the character of the slides varied greatly. When preparing sets of slides for public lectures for which the local managers provide Janterns, which have as a rule blow through jets, I try the slides on my 15-in. square aleet of cardhoard and reject any slides that do not show fairly well on il, but use those which pass this test, and I generally find that these show well on the larger screen used in the lecture-halls with the lime light. KER HK The Optical Lantern and the Human Mind. A Purenouoaists’ Virws, &c. \aee Optical Lantern now occupies a very important place in human affairs, and its importance is increasing in various ways. This is so hecause it provides the hest known means available for certain ends; some of which are as follows :— It is the most effective assistant to the voice When giving instruction in all subjects which adinit of pictorial illustration. The first thing necessary to the learning of any thing is to pay attention, and the Lantern particularly assists the untrained mind to do so, by shutting out of view the things that ought not to be attended to. One of the most common weaknesses is, inability to pay attention, inability to focus the thought upon one thing at a time, and keep it there. To focus anything means equally to exclude from something, as well as to concentrate wpon something. The habit of some people is to be, as it were, always looking sideways, not straight before them, with the result that there is a constant wncertainty, and want of connectedness in their thought and actions. Mental growth means increase in breadth of mental view, but, in the desire to know and understand everything, there is a risk of the mind becoming indefinite, “ Jack of all trades and master of none”’; so, in teaching, the governing principle should always be “ keep 2 clear focus,” or undivided attention on one subject ata time. To neglect this is like continuing to build a house upwards without regard to the foundations. Strong minds, like good houses, have good foundations; which means that the mind never loses consciousness of its relation to simple elementary things and facts. There would be much profit if people were more in the habit of reconsidering their foundations of frequently looking over their knowledge hox to see what was in it, and whether it was in order or confusion. To ask themselves where they were, what they were looking at, how many of the objects they can name, what qualities in them they can cnumerate, what colours, and what time it is, without looking at a clock. For it must he remembered that the thinking faculties work according to the knowledge they have to think upon. To those weak in the power of attention, the Optical Tantern comes as a great help, hoth by increasing the plainness of objects, and in shutting out of view things that ought not to be attended to. In the evolution of the theatre, common sense suggested the footlights, and placing the auditorium in darkness. Wagner saw that light and darkness could be utilized to aid the mind in apprehending matters presented to the vision, and he therefore directed that his operas should be performed with the auditorium in as much darkness as would prevent the people recognizing each other, and also that the musiclans and their instruments should not be seen, lest attention should be diverted from the proper subject. The law of attention requiring the exclusion of objects that might be within range of vision is possible of f much extended application. I once wrote to the minister of a fashionable suburban church, about the conspicuous position of the chief lady singer in the choir, and how her feathery hat diverted attention from the act of worship, suggesting the desirahility of modification in such. matters. He wrote me a very silly reply, (it is not impossible for clergymen to say silly things). He declared that the young lady had a ve ry good character, and wished that all young ladies were her equal, etc.; and never once referred to the subject of my letter. I wished that a Lantern could have been used to put the lady in darkness ! The experience of hymns being sung by a large congregation from the words thrown on a screen is decidedly in favour of such a practice. The