PROCEDURE. Say to the subject: "_You know, do you not, what it means when they say a gun 'carries 100 yards'? It means that the bullet goes that far before it drops to amount to anything._" All boys and most girls more than a dozen years old understand this readily. If the subject does not understand, we explain again what it means for a gun "to carry" a given distance. When this part is clear, we proceed as follows: "_Now, suppose a man is shooting at a mark about the size of a quart can. His rifle carries perfectly more than 100 yards. With such a gun is it any harder to hit the mark at 100 yards than it is at 50 yards?_" After the response is given, we ask the subject to explain. SCORING. Simply to say that it would be easier at 50 yards is not sufficient, nor can we pass the response which merely states that it is "easier to aim" at 50 yards. The correct principle must be given, one which shows the subject has appreciated the fact that a small deviation from the "bull's-eye" at 50 yards, due to incorrect aim, becomes a larger deviation at 100 yards. However, the subject is not required to know that the deviation at 100 yards is exactly twice as great as at 50 yards. A certain amount of questioning is often necessary before we can decide whether the subject has the correct principle in mind. SCORING THE ENTIRE TEST. _Two of the three problems_ must be solved in such a way as to satisfy the requirements above set forth. REMARKS. These problems were devised by the writer. They yield interesting results, when properly given, but are not without their faults. Sometimes a very superior subject fails, while occasionally an inferior subject unexpectedly succeeds. On the whole, however the test correlates fairly well with mental age. At the 14-year level less than 50 per cent pass; of "average adults," from 60 to 75 per cent are successful. Few "superior adults" fail. The test as here given is little influenced by the formal instruction given in the grades or the high school. In fact, 80 per cent of our uneducated business men, as contrasted with 65 per cent of high-school juniors and seniors, passed the test. Success probably depends in the main upon previous interest in physical relationships and upon the ability to understand phenomena of this kind which the subject has had opportunity to observe.