Dava Sobel’s Longitude is a pocket-sized book which manages to be a good read about a complex and, one might think, fairly unsexy subject: the problem of finding your longitude at sea. It is the tale of John Harrison, who, in the early 18th century and, in spite of his lack of formal education and status, invented the marine chronometer. Sophie’s World by Jostein Gaarder is a combination of novel about the theory of thought and a meander through the history of philosophy, which again seeks to illuminate very complex ideas for its intended teenage market.

Longitude is a function of time. To find it at sea, you need to know what time it is at some other known location on earth. So you take a portable clock with you which is set to “home time”. But in the early 18th century no one had invented a clock that was particularly accurate and not affected by a ship’s movement andtemperature changes.

It was a crisis that came to a head in l707 with the loss of four British ships and 2,000 men at sea, a catastrophe caused, at least in part, by sailors’ inability to know exactly where they were. A prize of Pounds 20,000 (equivalent to Pounds 1 million today) was offered for a solution to the problem.

Longitude traces the progress of John Harrison, from Lincolnshire, as he works at this riddle, producing one clock after another, each an improvement on the last, until he finally arrives at his final version which has been described as the most important timekeeper ever made.

It is a good yarn, although some critics have suggested that Dava Sobel has sacrificed a modicum of historical veracity for the sake of a good story. Jonathan Betts, curator of Horology at the National Maritime Museum in Greenwich, while not disputing that it is a good story well told, would like readers to be aware that perhaps Maskelyne, Harrison’s arch-rival, wasn’t quite as villainous as he isportrayed.

Betts admits that he can’t complain: the book has brought deserved recognition for an unsung hero and “brought people rattling through the turnstiles of the museum” - and for good reason. Four of Harrison’s timekeepers, H1, 2, 3 and 4, (there is an H5 elsewhere and there may be an H6; Harrison talked about a pocket-watch version, but it hasn’t been found) are displayed at the Royal Observatory, which was founded in 1675 by Charles II “in order to the finding out of the longitude of places for the perfecting of navigation and astronomy”.

If you want to know about longitude and time generally, this is the place. Exhibits abound, including a demonstration of what happens to an old-fashioned pendulum clock when you take it to sea and examples of previous attempts at gauging longitude, including the lunar-distance method, which uses the movement of the moon in the sky as a kind of clock. There are galleries displaying the Greenwich telescopes, illustrating the phases of the moon, eclipses and craters, and explaining “how stars tell the time” and much more.

Time doesn’t explicitly feature in the national curriculum, nor does longitude, but it is a subject which is obviously of fundamental importance and lends itself to cross-curricular study bringing in many targets. Moreover, the approach of the millennium has focused many educationists’ minds on the subject and on Greenwich’s unique position as the centre of both space and time. How this came about is also explained in the galleries.

The museum has many activities for schools including a very varied range of workshops at its different sites. It is also organising a large programme of events on time, the millennium and astronomy for the National Week of Science, Engineering and Technology l997 in March. This year and next there are two in-service training days for teachers covering subjects including longitude, the measurement of time, the millennium and the significance of Greenwich.

In June the museum will be repeating its drama presentation by Ross Interpretations about John Harrison. The performance takes pupils on a whirlwind jaunt through the Royal Observatory and through the story of Longitude, inviting their participation.

Philosophy, too, does not appear in the national curriculum but many feel that it is a discipline that could be incorporated into it. “There is a lack of philosophical knowledge at present. A lot of teachers feel there is a gap in their own knowledge,” says Karin Murris, consultant and course co-ordinator at the Wales Centre for Practical Philosophy at the University of Wales, Swansea.

Another book which recently became a bestseller might help them. Sophie’s World is a novel about the history of philosophy seen through the eyes of a young girl, the eponymous Sophie. Karin Murris already uses it in teacher education especially on summer schools for teachers and others interested in teaching philosophy.

“It’s a user-friendly introduction, and a lot of teachers have really enjoyed the book,” she says but, like many reviewers, she finds the approach of philosopher-teacher who takes Sophie on her voyage of discovery often too didactic and wonders at the choice of philosophers, for example, the inclusion of Freud and the omission of Wittgenstein.

Roger Sutcliffe, a teacher at Christ’s Hospital School in Horsham and secretary of SAPERE, an organisation which promotes philosophical enquiry in schools, incorporates philosophy into his English lessons. The book is not the kind of stimulus he tends to use: “I am keen for students to find their own questions”, he says.

Jostein Gaarder would disagree. Earlier this year Green Submarine, the English imprint of a German company, published a workbook for people aged 14 and over to encourage and enable teachers to use Sophie’s World as a classroom text. In his introduction to it Gaarder argues that “above all (the book) aims to make the readers aware of and understand the importance of asking philosophical questions”. The workbook as a whole demands a fairly exhaustive study of the text and it is doubtful whether it could be fitted into an an already overstretched curriculum. Moreover, some of it may strike teachers as over-earnest: for example it instructs users in how to create a thematic overview, an index and a glossary, a labour of love which could take weeks. But the photocopiable worksheets and activities, often accompanied by lively illustrations are fun and thought provoking.

At the least the novel will be a useful addition to children’s reading listing, providing them with an introduction to a subject many, like Sophie, will sadly know nothing about.

* National Maritime Museum, Park Row, Greenwich, London SE10 9NF. Tel: 0181 858 4422.Bookings: 0181 312 6651 * SAPERE (The Society for the Advancement of Philosophical Enquiry and Reflectionin Education) Roger Sutcliffe.Tel: 01403 242960. Karin Murris Tel: 01239 820440 * Workbook: Sophie’s World by Peer Olsen. Pounds 16. Published by Green Submarine. Distributed by Vine House Distribution, Waldenbury, North Common, Chailey, East Sussex BN8 4DR.

Tel: 01825 723398.

Education Show stand PV24