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

127of a combined microscope and polariscope, a demonstrating lantern forexperiments and spectrum work, and an ordinary projecting lantern,these three optical systems are attached to a rotary body of hexagonshape, the lamp remains stationary whilst each successive lantern isbrought into play, revolving on bearings which give it great steadiness,and not disturbing any pre-arranged experiment on the lanterns beingnot in use. When the arc lamp is not required the lime lightmay be made to take its place, and for ordinary purposes this is sufficientexcept in the case of high power microscopical work. When this formof lantern was first shown at South Kensington, by the late Mr. W. LantCarpenter, it met with the unanimous approval of the authorities, asbeing the most approved instrument for science work, and was fitted withthe Brockie Pell lamp at Mr. Carpenter's suggestion.Fig. 60.ARC LAMP FOR PROJECTION PURPOSES.The old Duboscq lamp needs no description, being incapable ofgiving a really steady light, and being more fitted for battery use with 40or more Grove or Bunsen cells, it will work fairly well for ordinary lanternpurposes.