The index has changed over the years in appearance and in how the indexing is done. (Note the hand-written very early years!)
During some periods the index was cumulated in 6-month blocks (Jan-June, and July-Dec). For older time periods there is first an "Editorial Index", i.e. an index to the editorial pieces, and next a "News Index", i.e. an index to the regular news stories. Many stories were listed under broad subject headings, such as "Education", or under the names of the cities, states, or countries where the news event occurred.
Recently, the editorials have not been separated from the news stories, but they are usually identified as such in the news summaries, and the subjects of editorials are listed under the subject heading "Editorials" in the index. Elsewhere they may be identified with the abbreviation - "ed."
When choosing an article, try to determine that it is fairly substantial, and not just a brief note. You cannot tell from the entry in the index how long the story is, but front page stories are likely choices. You may have to try a few to get one that will do.
How to read an entry in the old volumes of The New York Times Index.
Ice cap at North Pole: Removal by dynamite suggested by Mr. Dunsford. Ap. 26 4-6This is from the Jan-June 1890 section, so you know this is April 26, 1890. It is on page 4, column 6 (the sixth column from the left).
Note that some subject terms will sound familiar, such as "Murders and homicides", "Fashions", or "Strikes", while others may sound old-fashioned or baffling, such as "Swindles", "Prize fighting", "Temperance" (for alcohol abuse), or "The Turf" (for horse racing). "Automobiles" as a subject makes its first appearance in the index in Jan-June 1899, still vastly outnumbered by stories under "Bicycling affairs".
You will be surprised how many topics still of interest today you will find, disguised, perhaps, behind different terminology.
In later years the entries look like this: (From 1941)
Churchill says Germany must cut Brit ocean lifeline to win, radio s; text, Ap 28, 1:8; ed, Ap29, 18:1; Berlin reaction, Ap 29, 8:3