The next letter contains the first allusion to Isaac Sprague, so long associated with Dr. Gray as illustrator of his works. Isaac Sprague was born in Hingham in 1811. He early showed a faculty for observation, and a gift for painting birds and flowers from nature. His talent was discovered, and he was invited by Audubon in 1843 to join his expedition to Missouri, and to assist in making drawings and sketches. President, then Professor, Felton, having met him in Hingham, and knowing Dr. Gray was looking for some one for his scientific drawings, recommended Mr. Sprague, and he began with the illustrations for the Lowell lectures and the new edition of the “Botanical Text-Book.” Dr. Gray was delighted with his gift for beauty, his accuracy, his quick appreciation of structure and his skill in making dissections. Mr. Sprague was from that time the chief, and mostly only, illustrator for his books, both educational and purely scientific. Dr. Gray is said to have stated that Mr. Sprague had but one rival,--Riocreux; and he considered that draughtsman’s classical drawings inferior to Mr. Sprague’s. TO JOHN TORREY. CAMBRIDGE, March 8, [1845?] ... I finish Lichens this afternoon; and have next two lectures on Fungi and spontaneous generation to give. I interweave a good deal of matter, such as, on Ferns, the part they played in the early times of the world, à la Brongniart. Mosses, filling up lakes and pools; Sphagnum, Peat. Lichens, first agents in clothing rocks with soil. I have noble illustrations of rust in wheat, ergot, etc., and Sprague is now hard at work on smut, à la Bauer. You remember the letter I sent you from Prestele of “Ebenezer, near Buffalo,” and which you still hold. Well, he has sent me for inspection a most superb set of drawings, both of cultivated and of some native plants, exceedingly well done. Also specimens of his work in cutting on stone, which he does admirably. He did the work in Bischoff’s “Terminology,” which perhaps you remember, two quarto volumes. What a pity he did not have the State-Flora plates to execute! If Dr. Beck and yourself go on with your plan, he is your man to engrave the plates on stone. Our Illicium is now in full flower; but I cannot spare Sprague a moment to draw it yet; unless, indeed, it is quite certain you will want it this year, when I would try. He must work hard for me two weeks longer.... My cutting up of “Vestiges of Creation” was a fine blow, and told. Peirce, who you know was rather inclined to favor Rogers a while ago, is now sound and strong. We think of sending a critical analysis of the first part of Mulder, as our joint work (if he finds time to put in form the physiological deductions I give him), to the meeting of geologists and naturalists at New Haven next month.