Professor Adam Sedgwick, of Cambridge University, famous as a geologist, and Charles Darwin once took an excursion in Wales amid markings of extraordinary interest which neither of them noticed. Darwin tells us: “I had a striking instance of how easy it is to overlook phenomena, however conspicuous, before they have been observed by any one. We spent many hours at Cwm Idwal, examining the rocks with extreme care, as Sedgwick was anxious to find fossils in them, but neither of us saw a trace of the wonderful glacial phenomena all around us; we did not notice the plainly scored rocks, the perched boulders, the lateral and terminal moraines, yet these phenomena are so conspicuous that, as I declared in a paper published many years afterward, a house burnt down by fire could not tell its story more plainly than did this valley. If it had been filled with a glacier, the phenomena would have been less distinct than they now are.” At a later day when Darwin’s powers of observation had become acute in the highest degree, he noticed a bird’s feet covered with dirt. Rather a common fact, not worth dwelling on, earlier observers had supposed. Not so thought Darwin. He carefully washed the bird’s feet, and planting the removed solids he was rewarded with several strange plants brought from afar by his winged visitor. A cousin to Charles Darwin, Francis Galton, is an investigator of eminence. In a study of visual memory, a faculty in which observation bears its best fruits, he says:-- “It is a mistake to suppose that sharp sight is accompanied by clear visual memory. I have not a few instances in which the independence of the two faculties is emphatically commented upon; and I have at least one clear case where great interest in outlines and accurate apprehension of straightness, squareness, and the like, is unaccompanied by the power of visualizing.” A new instrument, machine or engine is imagined by its creator long before it takes actual form; everything he sees that will be of help he builds at once into his design, everything else, however interesting in itself, he passes with a heedless eye. Think Birds and You Shall See Birds.