Alger was the sole member of her class of protected cruiser built for the French Navy in the late 1880s and early 1890s. Alger was ordered during the tenure of Admiral Théophile Aube as Minister of Marine according to the theories of the doctrine. The ship was intended as a long-range commerce raider, and she was armed with a main battery of four guns, was protected by an armor deck that was thick, and was capable of steaming at a top speed of .
Alger served with the Northern Squadron early in her career, where she took part in routine peacetime training exercises. In 1895, she was deployed to French Indochina, returning to France in 1897 for a stint with the Mediterranean Squadron. Placed in reserve by 1901, she remained out of service for several years. Reports conflict over her activities in the mid-1900s, with contemporary reports placing her in the Mediterranean for fleet maneuvers, while later historians state the ship was on a second tour in East Asia from 1905. Both agree that Alger served in Asian waters as late as 1908. The ship was reduced to a storage hulk in 1911 and remained in the fleet's inventory until 1939, when she was broken up.
Design
The French naval minister, Charles-Eugène Galiber, drew up specifications for a new commerce raiding cruiser in mid-1885, which he submitted to the (Council of Works) for consideration on 12 June. The new ship was to generally follow the patter of the earlier cruiser , but slightly smaller and a revised armament. Unlike Amiral Cécille, which carried a large secondary battery, the new ship would carry only a few medium guns. The examined Galiber's proposal in a meeting on 15 July, and they approved it largely without changes, apart from increasing the displacement from to . Galiber took the revised specifications and forwarded them to France's shipyards on 21 July to request refined design proposals.
Eight shipyards responded by early 1886, which the examined in a meeting on 2 March. They accepted four of the proposals for further refinement, and on 31 July, two of these were formally accepted. The first, drawn up by Jules Thibaudier, became the ; the second, from Théodore Marchal, became Alger. Because they were approved at the same time and were generally similar, the two ships are sometimes considered to be the same class, and are referred to as the Alger class, but they are in fact different designs that vary considerably in their particulars. Unlike Jean Bart, Alger adopted Belleville-type water-tube boilers that had been successfully used aboard the unprotected cruiser , and her armament was arranged differently. Marchal adopted a hull form similar to the British cruiser , which had famously exceeded during her sea trials.
The original Alger was ordered on 13 October 1886, but on 29 October, this ship was renamed Dupuy de Lôme after a of that name was cancelled. A second ship was ordered to Marchal's design on 14 February 1887, which in turn received the name Alger. Dupuy de Lôme was cancelled on 16 August in favor of a third vessel, an armored cruiser, also named , leaving the second Alger the only member of the class to be built. After both designs entered service, the navy evaluated Alger and the Jean Bart class, finding the latter to have a superior hull form. Alger also proved to be more vulnerable to damage in heavy seas, as the sponsons for the main and secondary guns extended further from the sides of the hull. She also tended to take on water more than the Jean Barts.
General characteristics and machinery
Alger was long at the waterline and long overall, with a beam of at the waterline and over the sponsons. She had an average draft of , which increased to aft. She displaced normally and up to at full load. Her hull featured a pronounced ram bow and a tumblehome shape, along with a sloped, overhanging stern. The bow was not strengthened to allow the ship to ram an opponent, however. Alger had a minimal superstructure, consisting primarily of a small conning tower and bridge forward. The cruiser carried a pair of heavy military masts fitted with fighting tops for some of her light guns and observation positions. Her crew varied over the course of her career, amounting to 387–405 officers and enlisted men.
The ship's propulsion system consisted of a pair of 3-cylinder triple-expansion steam engines driving two screw propellers. Steam was provided by twenty-four coal-burning Belleville-type water-tube boilers that were ducted into two funnels. Her machinery was rated to produce for a top speed of , but on her initial speed trials, her engines reached from . She had a cruising radius of at .