Most diving work using standard dress was done heavy, with the diver sufficiently negatively buoyant to walk on the bottom, and the suits were not capable of the fine buoyancy control needed for mid-water swimming.

[3]: 554 Borelli designed diving equipment that consisted of a metal helmet, a pipe to "regenerate" air, a leather suit, and a means of controlling the diver's buoyancy.

[4] Inspired by a fire accident he witnessed in a stable in England,[5] he designed and patented a "Smoke Helmet" to be used by firemen in smoke-filled areas in 1823.

A long leather hose attached to the rear of the helmet was to be used to supply air – the original concept being that it would be pumped using a double bellows.

In 1834 Charles used his diving helmet and suit in a successful attempt on the wreck of Royal George at Spithead, during which he recovered 28 of the ship's cannon.

[7] Expanding on improvements already made by another engineer, George Edwards, Siebe produced his own design: a helmet fitted to a full-length watertight canvas diving suit.

[7] In France in the 1860s, Rouquayrol and Denayrouze developed a single-stage demand regulator with a small low pressure reservoir, to make more economical use of surface supplied air pumped by manpower.

The copper helmets and standard diving dress are still widely used in parts of the world, but have largely been superseded by lighter and more comfortable equipment.

[citation needed] Standard diving dress can be used up to depths of 600 feet (180 m) of sea water, provided a suitable breathing gas mixture is used.

Air or other breathing gas may be supplied from hand pumps, compressors, or banks of high pressure storage cylinders, generally through a hose from the surface, though some models are autonomous, with built-in rebreathers.

It tended to sit quite far forward, making it inconvenient except when looking down, but was quite popular among German amber divers, as they spent most of their time looking down at the bottom.

To add to this problem, a runaway ascent could cause sufficient internal pressure to burst the seal at the corselet, which could result in a loss of buoyancy, and the injured diver sinking back to the bottom in a flooded suit.

At the surface the diver could struggle a short distance using the arms, but underwater would normally walk on the bottom and climb up and down over obstacles, taking care to avoid passing under anything that could foul the air hose.

The front port can usually be opened for ventilation and communication when the diver is on deck, by being screwed out or swung to the side on a hinge and secured in the closed position by a wing nut against a rubber gasket.

[12] The corselet (UK), also known as a breastplate (US), is an oval or rectangular collar-piece resting on the shoulders, chest and back, to support the helmet and seal it to the suit, usually made from copper and brass, but occasionally steel.

An alternative method was to bolt the bonnet to the corselet over a rubber collar bonded to the top of the suit in the three- or two-bolt system.

Lead was the most common sole material, and a pair could weigh 34 pounds (15 kg) (more in the case of the US Navy Mark V mod 1 heliox equipment).

The diver tends to lean forward against the drag of the water when walking on the bottom, and could often not see where he was putting his feet, so the toes are capped, usually with brass.

Later, a speaking tube system, patented by Louis Denayrouze in 1874, was tried; this used a second hose with a diaphragm sealing each end to transmit sound,[13] but it was not very successful.

[24] A small number were made by Siebe-Gorman, but the telephone system was introduced soon after this and since it worked better and was safer, the speaking tube was soon obsolete, and most helmets which had them were returned to the factory and converted.

[28] Three bolt equipment, (Tryokhboltovoye snaryazheniye, Russian:Трехболтовое снаряжение, Russian:трехболтовка) consists of an air-hose supplied copper helmet that is fastened to a corselet and waterproof suit by three bolts which clamp the rubber neck flange of the suit between the metal flanges of the bonnet and the corselet, making a watertight seal between the helmet and suit.,[10] two 16 kilograms (35 lb) lead weights attached to the chest and back, heavy boots made of copper and lead, and a diver's knife.

[10] In twelve bolt equipment the rim of the corselet is clamped to the gasket of the suit, using brass brails to spread the load evenly.

The major components were: Spun copper and tobin bronze, 12 bolt, 4 light, 1/8 turn neck connection helmet with breastplate (corselet), clamps (brails) and wingnuts, weight 55 pounds (25 kg).

Lead soled boots with brass toe caps, canvas uppers with laces and leather straps weighing 17.5 pounds (7.9 kg) each.

Generally a shallow water helmet was a single item, which was lowered over the diver's head and rested on the shoulders, with an open bottom, so no exhaust valve was required.

This type of equipment is only acceptably safe to use at depths where the diver can simply lift it off and make a free swimming ascent to the surface in an emergency.

These helmets were Mk Vs modified by the addition of a bulky brass carbon dioxide scrubber chamber at the rear, and are easily distinguished from the standard model.

The helium helmet uses the same breastplate as a standard Mark V except that the locking mechanism is relocated to the front, there is no spitcock, there is an additional electrical connection for heated underwear, and on later versions a two or three-stage exhaust valve was fitted to reduce the risk of flooding the scrubber.

Flow rate of the injector nozzle was nominally 0.5 cubic foot per minute at 100 psi above ambient pressure, which would blow 11 times the volume of the injected gas through the scrubber.

Details would vary for other styles of helmet and weighting system: The diver would put on whatever thermal protective clothing was considered appropriate for the planned dive, then pull on the suit, assisted by the tenders where appropriate.