188 MEMORIES OF MY LIFE
which lay in the central line of totality, and commanded a grand view of the plain over which the shadow of the coming eclipse would sweep.
Thanks to the diplomacy of our interpreter, we obtained permission to use the flat roof of one of the highest houses, where we established ourselves on the morning of the eventful day. I had nursed with great care an instrument to observe the delicate variations of temperature. It was the invention of Sir John Herschel (1792-1871), who instructed me in its use, but its construction was so fragile that hardly any traveller had as yet been able to take one of them uninjured to its destination. I was no more fortunate than my predecessors, for the long stem of the heavy mercurial bulb broke. It was impossible to feel as unhappy as I ought to have been, because it left me free to gaze at will at the coming great sight.
And a wonderful sight it was, when the pure luminous corona first displayed itself at the moment of totality. It has been one of the great sights of my life. I made rude sketches in the dim light, and afterwards found that the closest representation of the eclipse was to be obtained by blackening paper over a candle and scratching out the lights, on the principle of mezzotints. I published a description of the eclipse in Vacation Tourists, with a sketch that has been reproduced more than once, but the curl given to one of the rays of the corona was not credited by most of my fellow-observers. Thus Sir George Airy, when lecturing on the eclipse at the Royal Institution and exhibiting my sketch on the screen, expressed in the most courteous way some reservation as to its acceptance as a true rendering. Photographs of subsequent