A NOVEL BLACKBOARD. 137 



sketch than by the most carefully prepared and elaborate 

 diagrams. He had used the ordinary black drawing- 

 boards for the Brixton lectures, and had found them to 

 answer his purpose fairly well in a comparatively small 

 room. But now, with the prospect before him of lec- 

 turing in large buildings, before audiences of perhaps 

 twelve or fourteen hundred, he clearly saw that some- 

 thing on a larger scale must be provided, if the effect of 

 his drawings was not to be entirely lost. Now what was 

 this " something " to be ? Clearly it would be of no 

 use to construct an ordinary blackboard of gigantic 

 dimensions, for the difficulty of carriage would form an 

 insuperable obstacle, while it would be at best but a 

 very clumsy piece of apparatus upon the platform. A 

 blackboard, again, upon the ordinary tripod stand has 

 no sort of stability ; a leg slips, or the whole thing is 

 unsteady, or perhaps even collapses with a run. Plainly 

 this would not do at all ; but the puzzle was to provide 

 a more efficient substitute. 



At length, however, after much thought, and a long 

 discussion with one of the engineers employed by the 

 Crystal Palace Company, the difficulty was overcome. 

 An iron framework of great strength, some seven feet in 

 height by eight in width, was constructed in such a 

 manner as to stand firmly erect when braced up by two 

 strong stays. In the central part of this framework, which 

 was grooved to accommodate them, were placed four 

 blackboards, fitting closely side by side, and so accurately 

 adjusted that a perfectly uniform surface was presented 

 when they were tightly screwed together. Ornamental 



