How technology and scientific invention reduce manual labor?

Technology, science, and invention do not do any such thing. The steam engine and the wind mill have been invented and forgotten several times in the last two thousand years, but they had no effect on manual labor because the religion in each case did not lead to their use. The steam engine and wind mill were invented in Egypt by a fellow named Hero. The religion at the time put the pharaoh first in every thought, and Hero could not think of any way that his toys would serve the pharaoh, so they were forgotten.

The inventions that are unique to the industrial revolution are:
* mass production, invented by Sam Colt to make pistols
* gonzo marketing, of which Diamond Jim Brady is the most famous example
* consumer financing, invented by Isaac Singer to sell sewing machines
* the savings bank, invented by Noah Webster

Prior to Mr. Webster, the dictionary guy, usury was condemned by almost everybody. Mr. Webster reasoned that it was ok for a man to own part of a business and to receive a portion of the profits, so it must be equally ok to deposit money with a steward who had a talent for investing in successful businesses. The depositor would not actually own a business, but he would have an interest in his steward's dealings and was entitled to be paid for his interest. Prior to that there was no such thing as retirement. People saved what they could of their earnings, or they hoped their children could support them, or they worked until they dropped. The savings bank was an obvious winner, and millions of people deposited their savings to get the benefit of compound interest, thereby providing huge amounts of investment money for new industries such as the recently reinvented steam engine.