Disc 15, 1950 April 12

This series consists of recordings made on USS Somersworth (EPCER 849), including some in collaboration with the USS Halfbeak. Testing and trials of Vertical Depth Sonar (VDS) appear to be the focus of this series. The sonar instrument is referred to as "fish". Series dates correspond to the end of Atlantis 160 and the start of Atlantis 161 cruises, yet no mention is made of either cruise on sleeves of the discs in the series. Some sleeves in this series mention specific pages in a log book, but this log book was not found in the WHOI archives. However, there are films in WHOI's collection corresponding to this series by Lee C. Davis, with the ship noted as USS Somersworth.