You have gathered several moves and sometimes travel miles before the Internet to check for state of the art. You must hook it up at a patent office not down the street, in Washington DC. It was a wonderful time and cost for enjoyable trips to our country's capital.
You would spend your time manually finding and examining the classification handbooks once there. A pushcart would be lugged to the stacks. And in each classification and sub-classification relating to your investigation, you would draw all the patent documents. A wonderful way to burn calories! Fitbits and Apple Watches had not been too bad back then.
Of course, in your sub-classification, your subject will be the one with hundreds of patents. So, you would bring a hulky stack of patents to a workstation and review every patent, only to find out that most patents were not applicable to your subject.
You have made a copy of the patents and put it back in your cart after you have buckled all the stacks to the appropriate prior art. However, you had to cross-reference the lists to make sure you had no missed items before you returned the records in the correct order in the stacks.
It has been a ton of work! Even to see if they figured, forbid Heaven, you might have overlooked a key condition of the art, you had to face a patent examiner for your machine. Then you had to conduct additional searches if you needed to search for foreign patents or unpublished literature. Investigate patents pending? Forget it. Forget about it. There was no way to discover which patents the works had. Have two patent checks been carried out? On a good day, eight hours.
It took a lot of timely (literally and figuratively) steps to perform a state-of-the-art search before the Internet so that you could do only one or two searches in one day.
Fortunately, from the 1990s, patent search is more and more efficient and productive, so that a comprehensive search can now be carried out in a few minutes or one hour, depending upon the subject. Fewer DC trips and patent investigator visits? Certainly. Do you have more time to work? Of course. Of course.