Edited sentence: Comment: Soil strength is very wide ranged from the N-value zero to super hard rock, and if the researchers would like to be able to analyze the wide range of data, the exponential scale will be easier.Comment: The hammer uses the accelerated force, and strong force tends to drive away everything.Measured data are neither linear scaling nor normal distribution, but logarithmic normal distribution.One can tell that there is a great difference in how the force is applied to a matter using a sledgehammer pounding or using a drill and slowly squeezing out.Public Works Research Institute of Japan has been indicating three major problems with the standard penetration test:.The method employees such a brute force method counting a number of blows of a sledge hammer, it cannot collect accurate data for weak soil layers.The results of the boring machines are limited to whole numbers for a specific driving interval.This is very true, and the use of sledgehammer is the source of the problem.This test uses a boring machine to present soil strength as N-value by driving a sampler into the ground for 30 cm by blows from a slide hammer, and N-value resolution is per 1m so data only represents 30% of entire depth