This letter was to replying Dr.M. K. Vainu Bappu for telling the improvements required in the spectra for H & K emission.

This item concerns about the rare white light flare recorded in hydrogen alpha at Kodaikanal Observatory. These observations were taken on photographic films or plates and digitized for scientific research purposes.

The fond contain correspondance of M. K. Vainu Bappu with C. V. Raman and mentors, donated by Mrs. Yemuna Bappu to IIA archives.

The item was about the original glass plate that recorded the "Evershed Effect" in 1909.