NDIA I OF CIENTISTS S man of few words, unassuming, a silent worker and a strikingly SiSerious bbusinessi apart, young DebendraD b d was a versa lle A handsome fi gure is how people who knew Debendra Mohan sportsman too. He was one of the founders of the Spor ng Union Bose describe him. Yet today very few even know about, let alone Club and the captain of the club’s hockey team in 1905-06. While remember, the man who was honoured in India and recognised a student of the Presidency College he excelled in cycling, football abroad for pioneering researches in the fi eld of cosmic rays, and cricket. ar fi cial radioac vity and neutron physics. Debendra Mohan’s uncle J.C. Bose had by far the most Debendra Mohan Bose built the fi rst indigenous cloud formidable infl uence in shaping his life and career. It has been chamber to track ionizing radia ons way back in the 1920s. He is tacitly assumed during his boyhood that Debendra Mohan would also remembered as the scien st who more than once came close undergo training in science to enable him to carry on his uncle’s to making major breakthroughs which later won the Nobel Prize. pioneering researches. But fate intervened. Debendra’s father died If one were to talk about forma ve infl uences on young in 1901. Now it became necessary for him to take up a profession Debendra there would be no dearth of it. He had illustrious peers to support his family. A er he passed his F.A. examina on from all around him. Debendra was born in Calcu a on 26 November Presidency College in 1902. J.C. Bose suggested that Debendra 1885. His father, Mohini Mohan Bose, who was a prac sing Mohan join the Bengal Engineering College at Sibpur. But a er one Homeopathic physician was among the fi rst Indians to have year of study there Debendra went down with a severe a ack of visited the United States of America. His uncle, Ananda Mohan fever and abandoned the idea of returning to the malaria-infested Bose, was the fi rst Indian Wrangler in Mathema cal Tripos from place again. Cambridge. Debendra Mohan’s mother was Subarnaprabha Bose, With the aim of moving on to the engineering college in younger sister of Sir Jagadis Chandra Bose, the renowned physicist Poona, Debendra got himself admi ed to the third year BSc class and plant physiologist. J.C. Bose lived in the same house with of Presidency College in 1903 with Physics as the main and Geology Debendra’s family at 64/1, Mechuabazar Street. For some me as one of the subsidiary subjects. He passed the BSc examina on P.C. Ray, the famous chemist and a close friend of J.C. Bose too with honours in 1905 and the M.A. examina on in Physics in stayed in the same house. 1906 standing fi rst in Calcu a University. For a year therea er In 1901 the family shi ed to 92/3, Upper Circular Road. P.C. he worked as a research scholar under J.C. Bose and obtained his Ray who had by then shi ed to 91, Upper Circular Road founded ini a on into his uncle’s inves ga ons in plant physiology. the Bengal Chemical and Pharmaceu cal Works. Young Debendra The very next year, in 1907, Bose got an opportunity to go to had the good fortune of interac ng with people like Nil Ratan England where he was admi ed as an advanced student in Christ’s Sircar, Rabindranath Tagore, Loken Palit, Sarala Debi, Charuchandra College, Cambridge. He worked in the Cavendish Laboratory for Du a and Sister Nivedita all of whom were regular visitors to P.C. some me under the guidance of Sir J.J. Thomson. Here he had Ray’s house. Debendra Mohan was also inspired by the renowned the opportunity of observing C.T.R Wilson develop his technique Swedish scholar M. Hammergren who had come to gather material of employing the cloud chamber for photographing the tracks of about Raja Rammohan Roy and the Brahmo Samaj. ionizing par cles. In 1910, he joined the Royal College of Science, SCIENCE REPORTER, JUNE 2014 54 SCIENTISTS OF INDIA A er joining the Bose After the death of Sir J.C. Bose, Ins tute in 1938 Bose took up a couple of years later he took the study of tracks of cosmic over the mantle of Bose Institute ray ionizing par cles using the as Director in 1938. He served photographic emulsion technique. the institute with rare distinction He determined the mass of mu for almost thirty years and mesons by this method. With the retired in 1967 when his health departure of his associate Bibha began to fail. Choudhri to England in 1945 this work was discon nued. Later on, Cecil Frank Powell, a Bri sh London from where he obtained in 1912 the A.R.C.S diploma as physicist was able to prepare well as B.Sc in physics with a fi rst class. such improved emulsions. On his return to Calcu a, in 1913, he joined the City College Powell was awarded the Nobel as Professor of Physics. Soon therea er, in April 1914, he was Prize in Physics in 1950 for his appointed Rash Behari Ghosh Professor of Physics at the Calcu a inves ga ons along this line. He University. Sir C.V Raman was a Palit Professor in the same actually acknowledged the priority of Bose and Choudhri’s work department. Besides, there were a number of brilliant lecturers about mu mesons during the course of his lecture at Bose Ins tute like P.N. Ghosh, Satyendranath Bose, Meghnad Saha and S.K. Mitra. some me later. Soon a er Debendra Mohan was awarded the Ghosh Travelling Professor Bose made a special study of the plant physiological Fellowship for two year’s advanced study in Physics abroad. He inves ga ons of Sir J.C. Bose who had shown that plants respond worked with Professor E. Regener at the Berlin University. to external s mulus. D.M. Bose suggested that there were certain Unfortunately, the First World War broke out and Bose biochemical processes that intervened between s mula on and got trapped in Germany for quite some me. However, he was mechanical response in plants. He ini ated the inves ga on allowed to con nue his studies under Professor Regener who regarding the source of energy of mechanical response in assigned him the task of construc ng a new cloud chamber. His plant organs, including the spontaneous pulsa on of leafl ets of training under C.T.R. Wilson proved useful. He managed to design Desmodium gyrans. a modifi ed Wilson-type cloud chamber to photograph the tracks Both as Professor of Physics in the University College of of recoil protons produced during the passage of fast alpha Science and as Director of the Bose Ins tute, D.M. Bose trained par cles through a hydrogen-fi lled chamber. However, he was not and inspired a genera on of scien sts. He ini ated several lines permi ed to present his PhD thesis un l the War ended. of inves ga on during his tenure. The me-varia on and al tude- During his stay in Germany Bose had the rare opportunity dependence of cosmic rays was measured using a Compton-Bennet of a ending the lectures of Max Planck, Albert Einstein, Rubens, type of Ioniza on Chamber. Several interes ng cases of sudden Warburg, Hertz, Max Born and others. Bose obtained his PhD varia ons in cosmic ray intensity associated with solar fl ares and (magna cum laude) degree from the Berlin University in March magne c storms were recorded. For work in neutron physics a 1919 and returned to Calcu a to resume his Ghosh chair at the 14.5 MeV neutron generator was fabricated and operated at the Calcu a University which he held ll 1935. In 1935, Sir C.V. Raman Bose Ins tute under Professor Bose’s guidance. Incidentally, it was le for Bangalore as Director of the Indian Ins tute of Science. the fi rst instrument of its kind to be installed in India. D.M. Bose succeeded him as Palit Professor of Physics. A er “Bose was a man of few words, and more or less a silent the death of Sir J.C. Bose, a couple of years later he took over worker, inspite of his vast erudi on and wide interest”, says S.D. the mantle of Bose Ins tute as Director in 1938. He served the Chaterjee, Professor Bose’s colleague. “He avoided both the ins tute with rare dis nc on for almost thirty years and re red in limelight of public applause and the patronage of the powers 1967 when his health began to fail. that be. His nature and his uncompromising principles were D.M. Bose’s main area of research was the study of nuclear praiseworthy.” collisions and disintegra on by means of Wilson cloud chamber Due to exposure to several cultural fi gures during his and photographic emulsions. He had seen C.T.R. Wilson develop childhood Bose evinced keen interest in social and cultural ma ers. his technique of employing the cloud chamber for photographing H was closely associated with the management of the City College the tracks of ionizing par cles. With the modifi ed cloud chamber and the Sadharan Brahmo Samaj. He served the Viswabhara he developed in Germany Bose was able to verify Darwin’s formula University as its Honorary Treasurer for about 18 years.