236 MEMORIES OF MY LIFE
was then etched by acid. The result was to produce quarto copper plates, each containing the whole of the instrumental data for each of the seven stations for five consecutive days. The original tracings are reduced to the ratio of 6 : i in horizontal and 2 : i in vertical measure. This work was steadily pursued for twelve years, which is long enough to include a complete cycle of solar sun-spots. The illustration is a facsimile of the upper two lines of one page, from which the fourth and fifth days have been removed, for want of space.
I t surprises me that meteorologists have not made much more use than they have of these comprehensive volumes. But there is no foretelling what aspect of meteorology will be taken up by the very few earnest and capable men who work at it. Each of them wants voluminous data arranged in the form most convenient for his own particular inquiry.
I take this opportunity of mentioning another attempt of mine which was not brought into practice but may hereafter be useful ; at all events, it is of interest. The object was to gain some knowledge of the upper currents of the air, such as are now being obtained by small balloons or kites, which carry self-recording instruments. It seemed to me that the cloud made by a bursting shell fired high in the air over the sea, at a little frequented part of the coast, as that of West Ireland, when no vessel was within the possibility of damage from falling fragments, ought to give what was needed. The first questions to be answered were as to the height to which a shell of appropriate size could be sent, the visibility of the result, and the cost of each