Dynamic buckling of stiffened cylindrical shells of revolution under a transient lateral pressure shock wave

A modal method of analysis is used to determine the response of an infinitely long stiffened cylindrical shell of revolution to a transient lateral pressure produced by an underwater explosion and propagating in an acoustic fluid. The shell is initially immersed, hence prestressed by the external hydrostatic pressure. A theory of dynamic buckling is then developed for cylindrical shells subjected to transverse pressure pulses of different durations.     

Helen F. Stuart and Hannah Frances Green: The Original Spirit Photographer

Spirit photographs are joint portraits that visually unite the bereaved and the deceased without use of a corpse. Arising from the same ideas that founded Spiritualism in the nineteenth century, these enchanted mementos are said to have been discovered by William H. Mumler in 1861, in Boston, Massachusetts. Spirit photographers typically worked with mediums who enabled the appearance of magical ‘extras’ of the deceased, and as the majority of mediums were women, their contributions to this development within personal mourning rituals have been limited almost exclusively to this activity. Fuelled by the acknowledged proximity of two women to the invention, Helen F. Stuart and Hannah Frances Green, this article challenges Mumler’s widely accepted status as the originator of spirit photography. Although Stuart was the owner of the studios where Mumler stumbled upon his invention and Green was a secretary and medium in the same studios, scholars have tended to refuse these women larger roles. This article establishes the viability of a new narrative, presenting the strong likelihood that these women were in fact one and the same person and proposing that this woman be recognised as a pioneer of spirit photography.