The HDT, in comparison with the three arm type CDM, has many advantages. However, due to its record being taken on magnetic tapes and fed into a computer, it requires some time until results can be obtained.
The writer has actually used the HDT recently and experienced the absolute need of hand comptuation from analog record. Therefore, the writer wishes to introduce the principle and methed of hand computation and the outline of machine computation, in order tc make a presentation of the difference between the two methods, and also to assist in the work of those persons engaged in well logging analysis who, the writer believes, will be having greater opportunities to come in contact with the HDT in the future.
