The White House correspondent for the Herald Tribune, Robert Donovan, first started thinking about the men who tried to take the lives of presidents of the United States when he encountered Collazo's attempt on Truman in 1950. He found the assassins a bizarre lot, as he searched for the causes of their violence and what happened to them. Seven times men have been known to attack presidents, and three times they have been successful; the influence of some has been far from what they expected. Guiteau, Garfield's assassin, who wanted a job and glory, brought on Arthur's organization of Civil Service; after Zolgotz' murder of McKinley, Secret Service protection became constant. Most of the men believed they were God's instruments -- Schrank, who assailed Teddy Roosevelt while campaigning, had dreamed that Roosevelt had murdered McKinley; King Dick Lawrence believed he had rights above Jackson. The Booth-Lincoln story is another of a road to recognition and glory clothed with fervor for the Confederacy. Zangara, whose stomach hurt him and who was anti-capitalist, went gunning for Roosevelt over Hoover simply because he was more conveniently located. Mr. Donovan points out that with the exception of the fanatic attempts of the Puerto Ricans, the strange, serious men who tried to kill our top executives have been severely unbalanced, for which we may be thankful. A subject with some drawing power.