After Dr. HUSKEY'S paper Prof. Hartree gave the following additional details of American machines:
1. In the RAYTHEON machine it is intended to use a pulse repetition frequency of 4 Mc/s and a carrier frequency of 30 Mc/s. The UNIVAC is to use a pulse frequency of 4 Mc/s. The EDVAC uses a 1 Mc/s pulse frequency.
2. In the storage system designed for the UNIVAC and the BINAC there are 30 delay channels in a drum of mercury. This form of construction is used to simplify the problem of temperature regulation. For the RAYTHEON machine a storage unit has been developed in which there are a number of channels in a rectangular box of mercury. Each channel involves several reflections from the sides of the box.
The WHIRLWIND will use electrostatic storage. Several American machines will use magnetic storage and there is a wide difference of opinion regarding the number of digits per inch that can be recorded. In the auxiliary store for the UNIVAC there will be 100 digits per inch whereas there will only be 10 to the inch in the magnetic drum store in the Harvard Mark III machine.