air drop them if we could, change to barges if the air drop did not appear feasible after tests. Therefore, a lettcr has gone from Bradbury to either Fields or Dean, stating these things. Bradbury has since talked to Bethe, but the results ofthis are not known. Ogle can only put it this way: as far as the Lab uy sure ce ory here is concerned, we are stremuously against this. If igton decrees that it be done we will air drop smething—cre not it go off, it may stop seme of the other shots and will alnost ,gan the other shots will be late, because we would have to con- centrate; on|ithis one at the expense of the others. the over-ahl The feeling is that position of the country from the point of view of having these Be Scoville and thaler explained the reasons for this proposal, First of all, the JCS have} in_recommending the deep underwater shot, specifically said they would like to/ctmpare the effects of such a shot with a surface shot in deep water, this)‘fo sea if the operational and development people can get away from depthjSharges, etc., altogether, (If they can do almost as well from the point of Liewof submarines and a task force array with a surface shot in deep water ith an underwater burst, this would change their concept.) Asked whet his is not amenable to’ calculation, Scoville replied that unfortunately there is no existing theory applicable to the calculation of underwater pres ej from a surface burst because all the calculations break off at the bo ‘layer. Thaler added that some work is now in process with scaled ch s, but it is not clear that results fram this will be applicable to mucl detonations. eR inother point is that one wants check the instrumentation that will be used in the deep underwater shot. ceplosives, that all the instrumentation will be checked by conventional esives, but proper checks require a time constant which is not ava able from conventional explosives. The participation in this test would not be p field test of the instmmentation as such, but against the conditions ovtaintt in Vigwan. The point, then, would be to measure underater pressures at same depth at which submarines might be, at some distance h this shot and Wigwam. The depth, according to Thaler, would be to or greater than 4, charge radii—_this is 0.135 times the cube root of | charge radius for HE; for a 5-MT yield, the depth would be around 1000 [fey He continued: the region of interest for submarines the range d calculate and having some estimate of the yield, th by scaling laws how far away the instruments should be. fy pointed out -15- eee