Sir Samuel Morland was one of the chief mechanicians of his time. Aubrey credits him with the invention of "drum cap-stands for weighing heavy anchors." It is admitted that he invented the speaking-trumpet - though Kircher disputed his claim - and two arithmetical machines, of which he published a description under the following title: 'The Description and Use of two Arithmetick Instruments' (1673). The arithmetical machines, originally presented to Charles II in 1662, were manufactured for sale by Humphry Adanson, who lived with Jonas Moore Esq. in the Tower of London. By means of them, the four fundamental rules of arithmetic were readily worked "without charging the memory, disturbing the mind, or exposing the operations to any uncertainty." This calculating machine appears to have been a modification of one constructed by Blaise Pascal about 1642. One of Morland's machines is now in the Science Museum in South Kensington. Pepys characterised one that he saw as very pretty but not very useful. A similar instrument seems to be indicated by No. 84 of the Marquis of Worcester's 'Century of Inventions.'

Morland's treatise on the speaking-trumpet is entitled: 'Tuba Stentoro-Phonica: An Instrument of excellent use, as well at Sea, as at Land' (1671). An advertisement states that the instruments of all sizes and dimensions were made and sold by Simon Beal, one of his majesty's trumpeters, in Suffolk Street. The tubes are stated in a French edition of the treatise published in London (1671) to be on sale by Moses Pitt for £2-5s each. One is still preserved at Cambridge University.

Morland's most important discoveries were in connection with hydrostatics, although the statement that he invented the fire-engine is untrue. He was only an improver of that machine. The problems connected with raising water to a height by mechanical means were receiving a great amount of attention during the middle of the seventeenth century, and to the discoveries made in this field (in which Morland bore an important part) are largely attributable the subsequent rapid development of the steam-engine and the accelerated rate of evolution in mechanical science generally. Morland may have had his attention drawn more particularly to this subject by Pascal's researches, which were then attracting attention in France, though Pascal's celebrated treatise 'Sur l'Equilibre des Liqueurs' was not published until 1663. It is certain that, from Morland's return to England in 1660, water-engines of various kinds occupied the bulk of his time and capital. On 11th December 1661, a Royal Warrant, was issued for a grant to Morland of the sole use, during fourteen years, of his invention for raising "water out of pits to any reasonable height by the force of air and powder conjointly". The method employed seems to have been as follows. An air-tight box or cistern was fixed at a height above the level of the water to be raised. A charge of gunpowder was exploded within this cistern, and the air expelled by means of valves; a (partial) vacuum being thus formed, the water is driven up from the reservoir below by the atmospheric pressure. The simple apparatus used was subsequently developed by Jean de Hauteville and by Huyghens (1679). In February 1674, a bill to enable Morland "to enjoy the sole benefit of certain pumps and water-engines by him invented" was read a second time in the House of Commons. The introduction of the bill elicited "Reasons offered against the passing of Sir Samuel Morland's Bill touching Water-Engines," in which it was urged that the inventor should have recourse to the ordinary letters patent for fourteen years. Morland published an 'Answer,' stating that he had expended twenty years' study and some thousands of pounds on his experiments. The measure, however, failed to pass, as did a similar bill in 1677, and he had to be content with a patent (No. 175, dated 14th March 1674). The pump in question, referred to as "raising great quantities of water with far less proportion of strength than can be performed by a Chain or other Pump," was apparently what is known as the 'plunger-pump,' the most important new feature in which is the gland and stuffing-box. This important contrivance, with which James Walt has often been wrongly credited, was undoubtedly the invention of Morland. With a cast-iron perpendicular-action pump of this nature it is stated that Morland, in 1675, raised water from the Thames sixty feet above the top of Windsor Castle at the rate of sixty barrels per hour by eight men. Elsewhere Morland states he raised twelve barrels of water 140 feet high in one hour by the force of one man.

An interesting schedule of his prices, with other papers concerning his inventions, is among the 'British Museum Tracts'. For a brass force-pump suitable for raising water from a deep well, he charged £60, and for an "engine to quench fire or wet the sails of a ship" from £23 upwards. Another very interesting and important evidence of Morland's inventive genius is supplied by a manuscript in the Harleian collection at the British Museum (No. 5771). This manuscript is a thin book upon vellum, written in elegant and ornamental characters, and entitled 'Elevation des Eaux, par toute sorte de machines, reduite a la mesure,. au poids, et a la balance' (1683). At page 35 is an account of what seems to be one of the first steps made towards the art of working by steam. It has this separate title: 'Les principes de la nouvelle force de feu; inventee par le Chev. Morland l'an 1682, et presentee a sa majeste tres Chrestienne, 1683.' The author thus reasons on his principle before offering a table of weights to be raised by cylinders half full of water, according to their diameters. Subsequently Morland printed a book in Paris, with the same title, from 'Elevation des Eaux' to 'a la Balance' (1685). In the dedication to the King of France, Morland says that as his majesty was pleased with the models and ocular demonstrations he had the honour to exhibit at Saint-Germain. He thought himself obliged to present his book as a tribute to so great a monarch. He states that it contains an abridged account of the best experiments he had made for the last thirty years respecting the raising of water, with figures in profile and perspective, calculated to throw light upon the mysteries of hydrostatics. It begins with a perpetual almanac, showing the day of the month or week for the time past, present, and to come, and it contains various mathematical problems and tables. This suggestion for the employment of high-pressed steam to raise water (probably by means of Morland's own force-pump) was doubtless brought forward in connection with the many schemes suggested for supplying Versailles with water from the Seine. There is no exact description of the engine proposed by Morland, but the project is of the highest interest as one of the first to demonstrate the practical utility of steam-power. Morland's experiments must have been conducted with great care and skill, his estimate that at the temperature of boiling water steam was about two thousand times more bulky than water being substantially confirmed by Watt after careful investigation some hundred years later. From one of the several medals that were struck in Morland's honour and are now preserved in the British Museum, it would appear that he had also seriously considered the possibility of employing steam as a prime mover in the propulsion of vessels. The medal in question represents a conical-shaped vessel on a square wooden base, floating upon the sea. In the side is inserted a long pipe or arm, and from the top issues steam. In the distance is a ship in full sail, and the legend is 'Concordes ignibvs undae'.