If photographs are one of the candles by which we read history, a blaze of light will be shone on the past from Friday at the British Library. Here a vast exhibition of 19th-century photography will give the public a taster for the first time of the extent of the library’s photographic treasures, which amount to nearly half a million images. Culled from these, 200 items will reveal a breadth of material from the dawn of photography to the present day, hinting at a collection so large that it seems extraordinary that it has remained in obscurity all this time.

Curated by the British Library’s head of visual materials, John Falconer, the diverse material has been marshalled into sections, the Points of View of the exhibition’s title. These take the viewer through the history and diversity of photography — foreign adventures, photography as art, the portrait, scientific photography, Victorian inventions, social documentary and, finally, fin de siècle.

Lovely little gems dot the show, such as the photograph taken by Don Juan Carlos, the Duke of Montizon, of the hippopotamus Obaysch that arrived from Egypt in 1852 to live in Regent’s Park Zoo. Obaysch caused immense excitement and doubled the number of zoo visitors that year, although numbers fell away when it was realised that the animal didn’t do much.

The exhibition is packed with curiosity and beauty, typified by some charming pictorialist photographs by Peter Henry Emerson, such as Coming Home from the Marshes (1886), that captured a rural way of life threatened by industrial development. Although they look relatively natural, Emerson always posed his subjects, placing them among the meandering waterways and bountiful hayfields of East Anglia. His platinum prints, washed with a wonderfully delicate flat light, were to become hugely influential on photographic styles and ideas in the latter part of the 19th century.

One of the most interesting threads running through the exhibition, though, is the photographers’ need to take pictures that had a purpose. Ever since the mid-19th century, when travel photographers such as Francis Frith set out to capture the sublime godliness of distant lands, their work has been defined more by its moral message and usefulness than by its aesthetic content.

Frith was one of the most commercially successful makers of photographic views of the Middle East — he made three extended journeys through Egypt and the Holy Land between 1856 and 1860, publishing the results in a series of volumes accompanied by descriptive historical texts. One of his finest photographs is The Rameseum of El-Kurneh, taken in 1857. It shows a group of Victorian Nile travellers posed in front of a theatrical backdrop of colossal ancient pillars and shattered stone torsos, inhabiting their space like actors on a stage. A doughty woman in long skirts and a pith helmet sits side-saddle on a donkey, while a tall Englishman of military bearing poses on a hunk of ancient stone, hat rakishly tilted, cane held lightly between thumb and forefinger, as he stares out with the nonchalant authority of imperial possession.

Frith raged against the plunder of antiquities, though he knew that the spectacular displays of rifled Egyptiana in the British Museum had been the making of the public museum in Europe. He hoped that his pictures would encourage tourists to visit the Nile rather than encourage the export of works from it.

By the mid-19th century photography was beginning to make the world feel a smaller place and, for the first time, accurate depictions of distant lands and peoples were being enthusiastically scrutinised in parlours and drawing rooms across the Western world. The Victorians accepted the photograph as an unimpeachable witness and busily broadened their horizons with images of India, Japan and China, great pageants of dramatic landscapes, noble monuments and romantic ruins, all of which reinforced notions of the exotic East.

A beautiful velvety photograph by Wilhelm Burger of a village near Yokohama taken in 1869 gives a highly picturesque view of Japan — a few thatched houses on the bank of a river, a boy fishing in the distance and, in the foreground, a young warrior talking to a monk. The wide river inches glassily by and the sun glints on the distant hilltops. It is the sort of image that would have been highly palatable to Western sensibilities, its romantic subject matter matched by its exoticism and its picturesque elegance.

India produced vast numbers of artistically distinguished photographs, many of them designed to portray the morally uplifting and educative role of the British presence, but also to calm an uneasy awe at nature’s wanton prodigality. Here was a large and unruly continent that needed taming, and one way of doing that was to take photographs that appeared to bring nature to order with a picturesque view.

Samuel Bourne was one of the most influential professional photographers working in India, and several of his landscapes are here, elegant compositions produced with great technical skill and showing a nation apparently under control.

Portraiture comes next, demonstrating that, for the general public in Europe and America, the genre was immediately seized upon as photography’s most seductive application, soon replacing the more expensive painted miniature. Portrait studios sprang up in every major city and large town, their business stimulated by streams of innovations, from photographic jewellery to cartes de visite.

Not only were personal and family portraits commissioned, they were also made and bought in inexhaustible quantities of celebrities — from royalty, the aristocracy and politicians to artists and salonistes; the inspirational role models to society.

Napoleon Sarony’s portrait of Oscar Wilde taken in New York in 1882 is typical of this type of celebrity portrait. Wilde sits in a louche velvet suit on a chair draped with exotic rugs, his head propped on one hand, his other hand holding a book. A soft enveloping light describes his cravat, his ring and his luxuriant hair, and the deep tiredness of his elegant slouch. The photograph was later used as the basis for an advertisement for a New York department store.

But even while this deeply romantic vision was being created, many Victorian photographers were setting great store by the camera’s resistance to romance. In the spirit of Fox Talbot’s manifesto for photography, The Pencil of Nature, photographers saw themselves as technicians of truth, men of science using their medium to codify and describe universal laws and to document the physical world. Taxonomic archives were created, the races of mankind were surveyed, time and motion were studied and other celestial worlds explored.

Industrial and technological developments were changing Western communities with railways, canals and public works being built, creating infrastructures for new markets and movements. The photograph, in its documentary role, played a part in recording and celebrating this expansive age. And the exhibition ends on this note of progress, with the invention of the Kodak camera, which was to make photography available to and affordable by the masses. If this is just a taster of the library’s collections, there are many more treats in store for us.

Points of View: Capturing the 19th Century in Photographs is at the British Library, London NW1 (www.bl.uk), from Fri to Mar 7

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