As official recorder of the Expedition (a job of which I was very proud even if it was hard work) I had to book all the Doctor’s calculations as well as his natural history notes. I have already told you something of temperature, air pressure, time and what not. A further list of them would have included the calculation of distance traveled. This was quite difficult. The Doctor had brought with him a pedometer (that is a little instrument which when carried in the pocket tells you from the number of strides made the miles walked). But in the Moon, with the changed gravity, a pace was quite different from that usual on the Earth. And what is more, it never stayed the same. When the ground sloped downward it was natural to spring a step that quite possibly measured six or seven feet—this with no out-of-the-way effort at all. And even on the up grade one quite frequently used a stride that was far greater than in ordinary walking. It was about this time that the Doctor first spoke of making a tour of the Moon. Magellan, you will remember, was the first to sail around our world. And it was a very great feat. The Earth contains more water than land. The Moon on the contrary, we soon saw, had more dry land than water. There were no big oceans. Lakes and chains of lakes were all the water area we saw. To complete a round trip would therefore be harder, even though it was shorter, than the voyage that Magellan made. It was on this account that the Doctor was so particular about my booking a strict record of the miles we traveled. As to direction, we had not as yet been so careful about maintaining a perfectly straight line. Because it was by no means easy for one thing; and for another, the subjects we wished to study, such as tree-music, tracks, water supply, rock formation, etc., often led us off towards every quarter of the compass. When I say the _compass_ I mean something a little different from the use of that word in the earthly geography. As I have told you, the magnetic compass which John Dolittle had brought with him from Puddleby did not behave in a helpful manner at all. Something else must be found to take its place. [Illustration: “_It was natural to spring a step that measured six or seven feet_”]