The world's largest collection of art, historical documents and natural specimens has never been fully catalogued. But now thousands of volunteers from around the globe are lending a helping hand to the Smithsonian Institution in the American capital Washington DC. Thanks to on-line crowdsourcing, more than 3,500 people have signed up since June to help in transcribing documents and artifacts, so they can be made available in digital format. Al Jazeera's Tom Ackerman reports from Washington DC. Subscribe to our channel http://bit.ly/AJSubscribe Follow us on Twitter https://twitter.com/AJEnglish Find us on Facebook https://www.facebook.com/aljazeera Check our website: http://www.aljazeera.com/