Nils Christensen and the dimensionless Rosenthal solution

Norwegian freedom fighter during WWII (skiing across the Sweden–Norway border), Christensen came to MIT post-war on scholarship to work with John Chipman on welding fluxes. His first doctoral thesis manuscript was lost — Tom relates Christensen's surmise that Soviet spies at MIT stole it; he redid the work in nine extra months. Later, laid up in a Trondheim hospital bed in the mid-1960s, he extended Rosenthal's solution to dimensionless form, published in the *British Welding Journal* (1966). Returned to MIT for a sabbatical in the early 1980s; now deceased.

He ended up after World War II as a professor at UCLA in materials science. But Rosenthal had an MIT connection. When he published these things, the original paper says Department of Mechanical Engineering, MIT, as his affiliation. Then in the mid-60s — you have a copy of this paper in your handouts — Nils Christensen from Norway came along. Professor Christensen extended the Rosenthal formula to dimensionless form. Here's Nils Christensen, Distribution of Temperatures in Arc Welding. He was at the Royal Institute in Trondheim, Norway at the time. He had some accident, was laid up in a hospital bed for a year.