Is Babbage the author? I rather think he would not be so careful in concealing his name.... [My mother made some curious experiments upon the effect of the solar spectrum on juices of plants and other substances, of which she sent an account to Sir John Herschel, who answered telling her that he had communicated her account of her experiments to the Royal Society.] * * * * * SIR JOHN HERSCHEL TO MRS. SOMERVILLE. COLLINGWOOD, _November 21st, 1845_. MY DEAR MRS. SOMERVILLE, I cannot express to you the pleasure I experienced from the receipt of your letter and the perusal of the elegant experiments it relates, which appear to me of the highest interest and show (what I always suspected), that there is a world of wonders awaiting disclosure in the solar spectrum, and that influences widely differing from either light, heat or colour are transmitted to us from our central luminary, which are mainly instrumental in evolving and maturing the splendid hues of the vegetable creation and elaborating the juices to which they owe their beauty and their vitality. I think it certain that heat goes for something in evaporating your liquids and thereby causing some of your phenomena; but there is a difference of _quality_ as well as of _quantity_ of heat brought into view which renders it susceptible of analysis by the coloured juices so that in certain parts of the spectrum it is retained and fixed, in others reflected according as the nature of the tint favours the one or the other. Pray go on with these delightful experiments. I wish you could save yourself the fatigue of watching and directing your sunbeam by a clock work. If I were at your elbow I could rig you out a heliotrope quite sufficient with the aid of any common wooden clock.... Now I am going to take a liberty (but not till after duly consulting Mr. Greig with whose approbation I act, and you are not to gainsay our proceedings) and that is to communicate your results in the form of "an extract of a letter" to myself--to the Royal Society. You may be very sure that I would not do this if I thought that the experiments were not intrinsically quite deserving to be recorded in the pages of the Phil. Trans. and if I were not sure that they will lead to a vast field of curious and beautiful research; and as you have already once contributed to the Society, (on a subject connected with the spectrum and the sunbeam) this will, I trust, not appear in your eyes in a formidable or a repulsive light, and it will be a great matter of congratulation to us all to know that these subjects continue to engage your attention, and that you can turn your residence in that sunny clime to such admirable account. So do not call upon me to retract (for before you get this the papers will be