The Chelsea bombing earlier this month was not the first time terrifying explosions have rocked New York City.

Wall Street was ripped by a bomb that killed 39 and injured hundreds in 1920. A bomb killed two NYPD officers at the World’s Fair in Flushing, Queens, in 1940. That same year “Mad Bomber” George Metesky began his 16-year reign of bombing terror in the Big Apple, which kept New Yorkers on edge until he was caught in 1957.

These acts of terror are a small part of a new book, “Undisclosed Files of the Police: Cases From the Archives of the NYPD,” an extensively researched and richly illustrated compendium of crimes of all sorts that have occurred from the 1800s through 2010 in the Big Apple.

The 319-page tome released this week is the work of authors Philip Messing, Robert Mladinich and Bernard J. Whalen, the latter an NYPD lieutenant. Mladinich is a retired NYPD detective. The three writers will be hosting a book event Wednesday night at the Mysterious Bookshop at 58 Warren St. in Manhattan, where they will discuss their collaboration in putting together a detailed look at crimes including bank robberies, notorious murders, kidnappings and sensational trials, as well as the first and second World Trade Center attacks.

With publication coming just over a week after the West 23rd Street bombing in Manhattan’s Chelsea district, the timing for the authors is rather eerie and fortuitous, given the various explosions they have chronicled.

“It is just the way it works,” said Messing, a New York Post reporter who has been a crime writer since 1978. Bombings have been a fact of life here, he said.

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“It is a thread that runs through New York’s criminal history, no doubt about it,” Messing said.

In the early 20th century, the Black Hand, a loosely connected group of Italian extortionists and killers who were the harbinger of the Mafia, used bombings. The Black Hand activity led to the formation of the NYPD’s “Italian Squad,” led by the fabled Lt. Joseph Petrosino, who was murdered in Sicily in 1909.

Petrosino’s unit was the forerunner of the NYPD bomb squad, which in its earliest incarnation thwarted an attempt by Italian anarchists to bomb St. Patrick’s Cathedral in 1914, said Whalen, a 35-year NYPD veteran. The squad used undercover officers and infiltrated the bombers clique, he said.

“It was a pretty fascinating story and I thought police did an excellent job,” Whalen said of the St. Patrick’s case.

The 1940 World’s Fair bombing was never solved and the motives behind it never determined.

Metesky’s 16-year bombing spree, which injured 15 but took no lives, was sparked after he was permanently injured in a boiler explosion at his electric utility job for which he got no compensation. Apparently, the authors report, Metesky didn’t file for disability benefits in time. Metesky was sent to a state hospital for the criminally insane after he was caught. He was released in 1973 and died in 1994.

Political terrorism was behind the Jan. 24, 1975, bombing of Fraunces Tavern in lower Manhattan that killed four and injured 63. Police discovered the carnage was the work of a Puerto Rican nationalist group known by the acronym FALN, which was seeking independence for the commenwealth island, the authors wrote. Several people were convicted in the case.

“Undisclosed Files of the Police,” has something for every crime aficionado, from Mafia buffs to those who are captivated by headline grabbing trials. Among the scores of events and people depicted: Judge Crater’s disappearance in 1930; the 1932 Lindbergh kidnapping; the 1957 mob hit on Albert Anastasia; the French Connection case of 1961; the Alice Crimmins murder trials from 1968-71; the subway gunman Bernard Goetz incident in 1984 and the murder of swimsuit designer Sylvie Cachay in 2010.