Have you ever wondered what a decasievert or a petahenry is? Why some symbols are written in capitals and others in lower case? What the difference is between ps and pS? How many ampere there are in a zettaampere? Or what Nikola Tesla’s nationality was? These and many other questions can be answered in Philip Bladon’s A Dictionary of International Units.
This book is a pleasure for those fascinated by scientific terminology and writing style – or indeed anyone with a critical copy editor. It also provides a perfect reference book for teachers faced with questions like “But why can’t I write ‘the car moved 10 ms’?” In fact, I wonder whether the book arose out of the author’s own experience as a science teacher.
This slim paperback (87 pages) begins with a list of units ordered alphabetically by symbol, followed by the same information ordered by unit name. Then comes a list of all SI units named after scientists (yes, those are the symbols written with a capital letter), with the scientists’ nationalities and dates.
The second part of the dictionary contains a selection of units for presenting data meaningfully. This selection is listed first by symbol (what does C/mm2 symbolise?), then by quantity (which units should I use for heat or angular momentum?). Be careful not to lose the erratum notice, however, in which pA and pC are correctly listed as picoampere and picocoulomb, rather than petaampere and petacoulomb, as on page 61.
Next comes a table of SI prefixes and factors (did you know the prefix yotta has the symbol Y and the factor of 1024?). The following section, on writing SI units and numerical values, includes rules such as avoiding capital letters (25 Ampere) or plurals (the car did not move 10 ms, but it might have moved for 10 ms), and how to express decimals (comma or dot?). The book concludes with a definition of the seven base units of the SI system.
A Dictionary of International Units is a delightful book that belongs on the shelf of any science teacher, editor or unashamed pedant. Whether you browse happily through it in a quiet moment or just consult it quickly, you won’t regret owning it.
Publication year: 2005