Prestressed Concrete Beams-A Rational Design Method

We have become accustomed to the pressure of the atmosphere in which we live and fail generally to realise the latent power it represents. But we have a simple means of recalling it to mind. If we consider a mountain lake, its waters also represent potential energy. To release this energy, all that need be done is to install a suitable plant (a hydro-electric station) at a lower point, where the waters of the lake exercise considerable pressures which can be utilised in work. In the same way, to “awake” atmospheric energy, it suffices to provide a source of low pressure (a vacuum unit) in relation to which the atmosphere acts as an infinite reservoir of compressed air. I. Leviant

In presenting the paper, Dr. S. MACKEY expressed the author’s regret that an arithmetical error involving the panel dimensions had occurred in Table 8 and was not discovered in time to alter the proofs. The authors had corrected this in the revised Table given below.