The Optical Magic Lantern Journal (January 1896)

The Optical Magic Lantern Journal and Photographic Enlarger. 3 qualities of a jet, it has been suggested that that jet which gave a light satisfactory for general exhibition purposes with the mininum consumption of gas should be considered the best. A horse may be strong, so may be a domestic flea, and if one were asked which were the stronger, would it be correct to say the horse ? for in comparison to its size, the flea is proportionately many times as strong. The mixed jet which gave the greatest amount of light consumed about 17 feet of gas per hour—this, of course, with a large nipple—whilst the lowest amount used by apy mixed jet was 11 feet, whereas a saturator with a small bore, used in conjunction with ether, used only about 4 feet of | gas per hour. Yet with all the gas expended in the former case, and the large size of the nipple, the illuminating power of the very finest mixed jet was only four times as great as the saturator with the small bore, and using about a quarter . } : | that the signals are audible, and being as @ rule the gas. To publish the names of the makers of the jets would hardly be right, but the following : the results of the | table of results shows experiments, which were not without interest, especially to those assembled. ICubic feet of! Results Arranged ' Gas con| Relation of illumination | in the order of sumed per in terms of — | Illuminating hour. | : Power. ; coe : | 2 ee ee re eee gl \° a la 22 2 el et = 143 1 i | | | é | : } ai{2 650 [7-3] 1-00 “75 TS) v4; 44 H 3} 7-60 (9-18)1°34 1-00... °..j) .. | 5,100, * | 10°25 Bp !| 2| 5°50 |6-40 1:00' -99.:99'-98) “58 | (| 3} 5°80 |9°60) 1-11) 1-00 ,,;.. 1 -. 19} -95} * | 10:00 o!; 8} 780 8-92}1:211:00, | | {| 3| 8-00 |8-64) 1-00; ‘99 4199: 59} 7] 72} * | OTT pf 8] 9:58 19-60} 1°51.1:00, | 4| 7-60 19-34) 1:00, “66 ,, 66; 40! 8) “60) * : 10:25 g| 9-87 19-60/2:15:1:00 EY 11] 5-75 |5-28| 1-00, -46.. 46: +28! 3] 598-64; 8-00 p!| 8]10:25 | * 11:00 60. ,,,.. | “60 i} sl 966) * (1-65'1-00..)../ ..) 218 |G-40, 5:50 Gl] 7 977 | * 11:00: -72: ,,° 4! °72t : 5, 950 | * |1381:00..°... .. | 6 “546-01 5°83 yz {| 9} 6r40 6-18) 1-00: 38 ,,:.. 38)! 7] 5/1000! * |2-66'1:00..°..: .. 1 1) 44/723; 650 z {{2{10:00 | = 1:00 95 4, 4, *95! 1! 511000 | * 11:05 1:00..1..° .. | 6; *40)5°E0; 6-00 z {| 6 5:83 6-01] 1-00! 54 ,,°..: 54) | (| 5:10:00 | * }1-85)100.. .... | 4) 409.34 7-60 K || 5/1025 | * 2501700, |} | : {| 6} 6-00 |5:50; 1-00 40... |. -40| 9] -38/6-18! 6°40 z,! |. 5]10°25 | * 3-9C: 1-00; y.0-. 1-00) | i (|LO'Bther 4°16] 1:00, 26 ,,;.. . 26/11) +28)5-26) 5°75 wall ass Sodou. we ae). NO! -2614-16' Ether * Denotes that more than ten feet of gas were being used. A Noiseless Electric Signal. By C. Hiaes. Oxr of the many trifles that go towards the success of a lantern entertainment is an efficient means of communication between platform and lantern. The usual signal—a red light shown | at the back of the lecturer’s reading lamp—has the drawback of being equally visible to the whole audience as to the operator, for whom alone it is intended. The use of a hand-bell on the reading desk has an even worse effect. To avoid this distracting influence, many have adopted a portable electric bell, placed close to the lantern, with a flexible wire leading from the platform. This is an improvement on the old plan, but still it is open to the objection sent during a pause in the reading, are distinctly heard by everyone within range. What is wanted is a signal which shall inform the lantern operator alone of what is to take place, and which shall not require so much of his attention as the red light on the reading | lamp. These requirements are carried out in | an arrangement I made some time ago, which could be put togetber by any reader of this Journal possessing a slight knowledge of electrical apparatus, with the same success as has attended my own working. The apparatus consists of two or three “dry” batteries in one compartment of a wooden case, | the other and smaller compartment having a glass cover or lid, and containing a small electric “fairy” lamp, connected with a push and flexible cord. The case containing the battery and lamp are placed in some convenient position near the lantern, and the push near the lecturer’s hand on the platform, the wire being slung over gas brackets and other projections out of the way. Signals are sent in the same way as on an electric bell, by pressing the push button for a second or so. Before enumerating the purchases that will have to be made, a point to be settled is the | number of batteries required. This will depend on the “voltage” of the small incandescent lamp. A lamp taking only two volts can be worked with a couple of batteries, but the light is very small. A four volt lamp with three batteries is better, and a four or five volt lamp with four batteries better still. The reader must be guided by circumstances as to which of these combinations will be the most suitable in his case. Perhaps, however, the second is best,