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more likely that we have not fully appreciated the complexity of the problem. This much may be said for the possibilities of harmonic synthesis by electronic systems. Even with oscillators exhibiting linear performance, it requires relatively few of them, even without intercoupling, to produce complex patterns. The additional possibility exists of operating them in nonlinear fashion as individual harmonic generators. It may be of interest to note that Pepinsky has made notable progress in the crystallographic field by a related approach in which Patterson diagrams can be synthesized and presented on an oscillograph. Andrade was not altogether facetious when he once remarked that "the elucidation of atomic structure by measuring the light which an atom emits is much like asking an individual who has never seen a piano to envision its size, shape, and appearance by listening to the sound which it emits when it is thrown down a flight of stairs." Physical analogs and models have been very useful on occasion. While it is true that the behavior of very simple polyatomic molecules can be described accurately in quantum mechanical terms, this is out of the question for a thing like penicillin. For one thing, the computational difficulties increase prohibitively as molecular complexity increases. One wonders, however, to what extent high speed electronic computers may provide some solution by a straight forward, albeit lengthy computational process. Then too, the stochastic approach, in which a huge number of shrewd guesses are made at high speed, has its possibilities. Just what the criterion of the correct guess would be is probably the most difficult question. It seems to us that there is a considerable need for more inquiry into the empirical relations which might be found for infrared data. It is evident that empiricism will be necessary for some time to come, but almost any generalization would be very useful. The industrial analyst has a full day's work before him and continues to consult his punched card index, record his findings, and dash on to the next chore. The academic investigator may spend months or years in unraveling structural details of a single molecule. In the interim, the analyst's general requirements are not met, because he can decide, with certainty, on a structure only if it previously has been recorded. Instrumentation continues to improve the techniques used in infrared studsie, but it may well be called upon to solve some of these more general questions.
