Many years of saving had enabled him to finally buy one of the Holophane globes, with the Welsbach mantles invented by the German Carl Zeiss. These sources of light were absolutely the best for any scientist interested in studying optics. The Welsbach mantle consisted of a series of very think threads of fiber woven into a long, thin tubular mesh, which was then thoroughly impregnated with a mixture of thorium nitrate and cerium nitrate.

When exposed to gas it glowed brightly, and thus considerably increased the output of specialized gas lamps. Surrounding the glowing mantle was a globe of glass specially ground to have a lens-like pattern on its surface. Light leaving the mantle passed though the globe and was evenly distributed in all directions, free of distortion or hot spots.

Rosenstrauch took his valuable light source out of a box and attached it to the end of a long rod that stretched the length of his darkened workshop. Then he cleaned the Fraunhofer prisms - still the best in the world - turned up the light and began to crank the handle.

With a soft 'whirring' sound, the toothed wheel mounted vertically on the bench began to rotate. Keeping his rate of turning as steady as he could, Rosenstrauch put his eye to the series of lenses that acted as a detector and eye piece. If all went well ---

But again, as in many nights before, it did not. No matter how hard he tried, Rosenstrauch could not align and adjust the interconnected pieces of his equipment so that the light from the globe struck a piece of flat glass, went through the rotating wheel, passed though two sets of lenses, bounced off a mirror, returned to the wheel and then onto the detector. It was just too hard. Move one piece even slightly and the settings of all the other pieces of the system had to be changed again.

Rosenstrauch sighed, put away the Holophane globe, and turned his attention to Brother Gregory's broke microscope. At least here was something he felt sure he could fix.