the mirror.  One night, in a very high wind, Herschel had scarcely descended from his station before the whole apparatus came down; and his sister was in continual apprehension of some serious accident.  One such, indeed, occurred, and to herself.  The evening of the 31st of December had been cloudy, but as a few stars shone forth about ten o’clock, hurried preparations were made for observing.  Herschel, standing at the front of the telescope, directed his sister to make a certain alteration in the lateral motion, which was done by machinery, on which the point of support of the tube and mirror rested.  At each end of the machine or trough was an iron hook, such as butchers use for suspending their joints of meat; and having to run in the dark across ground covered a foot deep with melting snow, Miss Herschel fell on one of these hooks, which entered her right leg above the knee.  To her brother’s injunction, “Make haste!” she could answer only by a pitiful cry, “I am hooked!” He and the workmen hastened immediately to her assistance, but they could not disentangle her without leaving nearly two ounces of her flesh behind.  For some weeks she was an invalid, and at one time it was feared that amputation might be necessary.

* * * * *

Not satisfied with the magnifying power of any of the instruments he had hitherto constructed, Herschel resolved, in 1784, to attempt a forty-foot telescope.  Such a work, however, was far beyond his limited private resources; and he did not venture to undertake it until promised a royal bounty of L2000.  Then he removed from Datchet to Clay Hall, Old Windsor; and again, in 1786, to Slough, where he finally settled, and succeeded in erecting a commodious and well-equipped observatory.  “We may confidently assert,” says Arago, “relative to the little house and garden of Slough, that it is the spot of all the world where the greatest number of discoveries have been made.  The name of that village will never perish:  science will transmit it religiously to our latest posterity.”

At Slough, as at Datchet, prevailed the most enthusiastic industry; and the house was soon as full of well-ordered labour as a bee-hive.  Smiths were kept constantly at work on different parts of the new telescopic leviathan; and a whole troop of labourers was engaged in grinding the tools required for shaping and polishing its mirror.  Had not a cloudy or moonlight night sometimes intervened, Herschel and his sister must have died of sheer exhaustion, for they toiled with unremitting ardour both day and night.  With the morning came the workpeople, of whom no fewer than between thirty and forty were at work for upwards of three months together:  some employed in felling and rooting out trees, some digging and preparing the ground for the bricklayers, who were laying the foundation for the telescope.  Then there were the carpenter and his men; and, meanwhile, the smith was converting a wash-house into a forge, and manufacturing complete sets of tools for his own share of the labour.  In short, the place was at one time a complete workshop for the manufacture of optical instruments; and it was a pleasure to enter it for the purpose of observing the fervour of the great astronomer, and the reverent attention given to his orders.