The art of ballistics, until the total mechanisation of warfare in the twentieth century, had been, one might say, a hit and miss affair. In a series of experiments between 1864 and 1880 the Reverend Francis Bashforth related air drag to velocity and produced the first firing tables to be consulted on the battlefield as a guide to the ranging of artillery pieces. These tables were refined by a French military commission working in Grave but, at the onset of the First World War, there was still a lot of guess work involved. Many factors were simply not calculated. Since, without firing tables, any artillery weapon is much reduced in utility, the Americans took ballistics very seriously and established a tradition of research in the aftermath of that war. At the Aberdeen Proving Ground a succession of highly educated ballistics officers appeared during the 1920s and 1930s and it was these officials who moved to acquire a Bush differential analyser as detailed above.
Nevertheless, despite these preparations, the ballistics work generated by the Second World War was overwhelming. Each firing table for every new weapon required the tabulation of dozens of factors across thousands of possible trajectories, any one of which represented half a day’s work for a human computer with a desk calculator. By the summer of 1944 the computing branch of the Ballistics Research Laboratory was producing fifteen tables a week, but the need was for forty (Wulforst 1982:60). This, the so-called ‘firing table crisis’, was the supervening necessity for a fully electronic complex difference analyser, the machine which became known as ENIAC. Professor John Brainerd, the Moore School’s official ordnance liaison officer, wrote: ‘The proposed electronic difference analyser would, if successfully developed, not only eliminate such delays but would permit far more extensive ballistic calculations than are now possible with existing equipment’ (ibid.).