This collection contains two letters written in 1897 and some handwritten notes from Professor Silvanus Thompson. The letters are addressed to Professor Wilhelm Röntgen and largely concern Thompson's involvement with the Röntgen Society of London. The handwritten notes include a timeline of various scientific events and discoveries. In the first letter, dated August 1897, Thompson discusses the newly-formed society dedicated to the study of X-rays, the Röntgen Society of London. The society had elected Röntgen as the first honorary member, and Thompson writes to ask if the society can write Röntgen's name on the society roster. In the second letter, dated October 22, 1897, Thompson writes to Röntgen as the recently-elected president of the Röntgen Society of London and encloses the official acceptance letter of Röntgen into the society. Furthermore, he invites Röntgen to the society's next general meeting in November. Thompson offers Röntgen a place in his home if Röntgen were to travel to London for the meeting. In addition, Thompson asks if Röntgen could send some of his equipment used to detect X-rays should he not be able to come to the meeting. In addition to the two letters, there is also a handwritten timeline of scientific discoveries, presumably written by Thompson. Dates range from 1897 to 1930.