The Art of projection and complete magic lantern ... - Yesterday Image

1^3Fig. 54.A cheap but none the less efficient form of demonstrating lanternfor class work and small audiences, is shown and entitled " The Teachers'Aid." The space between the condenser and front lens is entirely open,for the introduction of tank and other experiments, an elevating tablecapable of being raised and lowered is held in position by a thumbscrew, it also slides along the two rails to suit the object beingshown. The distance between the condenser and front objectivemaybe extended or reduced at will, the rods holding the front andbody together are telescopic.In demonstrating experiments, it is important they should be placedas near the condenser as possible, especially when oil lights are used thecloser the object is so placed the brighter the disc ; a short focusobjective is preferable to a long one when oil is used for the same reason.When using oxyhydrogen we can afford to sacrifice a little light, butnot so with oil. A microscopic attachment is well adapted to this formof lantern as itenables the microscope to be brought much closer to thecondenser, and with this there is a gain in light. When using the