Submarine Command (1951): Download Magnet Link
Daniel and his staff began to look for something that was more robust, something that offered the potential for greater reliability and a wider range of applications. They concluded that there was only one possible material: the permeable ferrite core of the magnetic core used in many of the transformers on Navy aircraft. Daniel was able to obtain samples of the material from the good European manufacturers of transformer cores. Because of the high price and technical difficulty of producing such a material under government contract, the Navy was uninterested in the technical results until Daniel could show that it was feasible to produce large quantities of the material in the United States. Daniel was given his wish. He obtained a contract with the US Ordnance Department to produce the magnetic core material. The contract was for a modest amount, but it was a start.
Submarine Command (1951): download magnet link
The first breakthrough for the Specials came when Harrison and Forrester learned from Daniel about the work of the inventor of magnetic cores, Howard P. Russel. In 1917, while working as an engineer with Thomas Edison, Russel had experimented with making a coil of wire twisted to a tight pitch and winding this tight pitch of wire around an iron core. This process of electrically winding the wire around a metal core worked well, but was too expensive to become the general method. However, the process of winding a wire around a metal core was still the basis for the construction of transformers. The twists produced in the process were unreliable, and the tight pitch of the twisted wires was later found to be too difficult to replicate perfectly. This problem was solved by the development of ferrite and the discovery of a process for manufacturing it in large quantities. The ferrite was then used in transformers, and it rapidly became the material of choice for the construction of transformer coils.