YOU can't always judge a book by its cover . . . particularly this large, polished and carved wooden book.

It is full of dried ferns from a country at the other side of the world, The book, full of pressed New Zealand ferns, is kept safe in the botany department at Bolton Museum and Art Gallery.

And it is this week's featured item in our series on the Hidden Treasure at the museum fascinating exhibits not currently on show because of lack of space.

In the botany department's case, most of the examples of ferns, grasses and seeds are not on public show, but are viewed by schools and visiting experts. But they can be seen by appointment.

Keeper of botany Patricia Francis said: "This Book of Ferns is a really unusual object.

"It is exceptionally large (18 inches by 12 inches) and very heavy and its 60 pages are covered in pressed fern fronds every page is different.

"It is called a specimen book and displays a total of 118 different fern species, each one carefully arranged and labelled.

"The outer book covers are made of wood which is beautifully polished and carved.

"These specimen books were produced commercially so this object is not unique, but it has been examined by experts and is considered to be a very fine and very old example of its type.

"It was made by an E. Craig of Princes Street, Auckland and it is thought to date to around 1887.

"It is the only example known with gold blocked lettering which is on the leather spine of the book bearing the words New Zealand Ferns. The ferns themselves are still amazingly well preserved, despite their age. This book was obviously a very high class souvenir bought by a traveller, the pressed ferns forming a better memento than photographs or drawings would have provided."

There were six known manufacturers of these books. In New Zealand today, there are 180 different types of fern and 128 of these are known to be featured in these historic specimen books. The book at Bolton Museum was donated to it in 1909 by Alderman W. Smith of "Eastwood", Radcliffe Road, Bolton.

The museum does not know if Alderman Smith himself travelled to New Zealand, or if someone brought it back to him as a gift.

Travel to New Zealand at that time would have been difficult and would have involved a long journey by sea.

New Zealand is one of the few temperate areas of the world that has such a range of ferns from the enormous tree ferns to tiny "filmy" ferns. People who visit New Zealand today will still be amazed at the luxuriance of the ferns they will see.

The Museum would be interested to know any further information about Alderman W. Smith and his travels. Please contact the botany department if you can help.