Henry Humphrey Books

When Is Now?: Experiments With Time and Timekeeping Devices

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Gives directions for making several time-keeping devices such as a sundial and water clock and discusses some ancient knowledge about measuring time.

When is now?

By Henry Humphrey

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Gives directions for making several time-keeping devices such as a sundial and water clock and discusses some ancient knowledge about measuring time.

What is it for?

By Henry Humphrey

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Explains the function of common city objects whose purpose is often not understood, such as manhole covers, "not for deposit of mail" boxes, and standpipe connections.

What is it for

By Henry Humphrey

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What's inside?

By Henry Humphrey

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Photographs and text reveal the inside of a lighthouse, ambulance, tugboat, safety-deposit vault, telephone exchange, bakery, and several other interesting sites.

Sailing the high seas

By Henry Humphrey

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Describes the 12-day voyage of 4 crew members aboard a ketch from Oriental, N.C., across the Atlantic Ocean to the Caribbean island of Antigua.

The farm

By Henry Humphrey

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A look at the everyday life and work on a contemporary dairy farm.

The farm

By Henry Humphrey

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A look at the everyday life and work on a contemporary dairy farm.

How to Convert ISBN-10 to ISBN-13 (and Vice Versa): A Complete Guide

If you’re in the world of books—whether as a publisher, librarian, bookseller, or avid collector—you’ve likely come across the terms ISBN-10 and ISBN-13. Understanding these formats and knowing how to convert between them is essential for maintaining consistency and compatibility in book records. In this post, we’ll cover everything you need to know about ISBN conversions, step by step.

What is an EAN and How Does it Relate to an ISBN?

If you’ve ever purchased a product online or in a store, you’ve likely come across a barcode. Behind these barcodes lies a standardized system that makes modern commerce possible. Two key codes often encountered are the EAN (European Article Number) and ISBN (International Standard Book Number). But what are they, how are they connected, and why are they so crucial? Let’s explore.