the Penrose Annual, Volume X, 1904–05, mentioned about him in an editorial note that, "Mr. Ray is evidently possessed of a mathematical quality of mind and he has reasoned out for himself the problems of half-tone work in a remarkably successful manner ... (His printing developments) enable the operator to do uniform work with the fullest graduation and detail in it and with the minimum amount of manipulative skill in the negative-making and etching." The Penrose Annual Volume XI of 1905–06 published his paper about the new technique of 60-degree screens in halftone blockmaking. Author "Cheleder Ramayana" was the first book by Upendrakishore Roychowdhury. Upendrakishore embraced the liberal religious movement of Brahmo Samaj in 1883, after the death of his foster-father and was a deeply religious man, but his scientific bent of mind is reflected in the numerous science articles he wrote for children. He published two books on popular science, which were classics in the Bengali language. "Sekaler Katha" described the geological history of Earth and the ancient animals like dinosaurs. "Aakasher Katha" was an enthralling account of astronomy. His scientific interests were further nurtured by his close friendship to the scientists Jagadishchandra Bose and Prafullachandra Ray, all of whom lived and worked very close to each other. He also published a well known collection of children's stories called Tuntunir Boi. He further wrote Gupi Gyne, a fantasy novel (later adapted into the film Goopy Gyne Bagha Byne); essays like Daasotto Pratha (regarding slavery in the United States), Sandow (on Eugen Sandow) etc and travelogues like Puri, Abar Purite (on Puri, Orissa), Megher Muluk (on Darjeeling). One of his written book is Chotoder Shera Biggan Rochona Shongkolon. Also a musician, Upendrakishore wrote two books about music in Bengali – Sohaj Behala Shikkha, about learning to play the violin, and Sikhak Batorike Harmonium, about learning to play the harmonium as an accompaniment to Indian music. These were published by Dwarkin & Son, which was a famous music firm of the times, established by Dwarkanath Ghose, the inventor of the hand-harmonium. (Upendrakishore coined the name for the firm in 1875). His children Upendrakishore's eldest daughter, Shukhalata Rao, became a social worker, children's book author, and editor of a newspaper, Alok. She founded the Shishu-o-Matri Mangal Kendro (Centre for the Welfare of Children and Mothers) and the Orissa Nari Seva Sangha. His eldest son was famous Sukumar Ray. His second daughter was