THE LAW; Lincoln as Lawyer: Transcript Tells Murder Story

In the summer of 1859, a year after he was defeated by Stephen A. Douglas for the United States Senate and less than a year before he received the Republican nomination for President, Abraham Lincoln spent four sweltering days, from Aug. 31 to Sept. 3, in the Sangamon Circuit Court here in his hometown, successfully defending a young man named Peachy Quinn Harrison against a charge of murder.

A nearly 100-page handwritten transcript of that trial has just come to light, the only one known to exist among the thousands of civil and criminal cases that engaged Lincoln in his 24 years as a circuit-riding lawyer. It reveals a shrewd courtroom advocate nothing like the rustic rail-splitter of Lincoln mythology.

''The transcript tells us a good deal about Lincoln's courtroom manner,'' said John Chapin, a Springfield lawyer who is chairman of the advisory board of the Lincoln Legals, a new research project that seeks to find and eventually publish every Lincoln case. ''It shows he was painstaking about details, probing in cross-examination and low-key in style. His language was informal, to keep the jury on his side. But was Lincoln a hick lawyer? He was anything but!'' Search for Smallest Detail

James T. Hickey, former curator of the Lincoln Collection in the Illinois State Historic Preservation Agency, said, ''Most trial court cases in the 1850's were summarized, not transcribed. The transcript shows how carefully Lincoln prepared a case, probed for the smallest facts and built up a self-defense argument for his client.''

The ribbon-tied transcript had been kept in a mouse-chewed shoebox in a garage in Fresno, Calif., where Mr. Harrison's great-grandson, now dead, once lived. The document was later removed by its owner to a private home in Huntsville, Ala. The great-grandson's widow, who prefers anonymity, was persuaded to provide a copy to the Lincoln Legals for history's sake.

''It's the most important discovery that has turned up in the field of Lincolniana in many years,'' said Cullom Davis, a history professor at Sangamon State University in Springfield who directs the Lincoln Legals.