Looking today at the massive scale and crudity of early atmospheric engines, we find it hard to imagine that Newcomen was working at the limits of engineering technology available to him. The cylinders in particular were difficult to bore accurately, a problem which remained for many years. An account for the construction of an atmospheric engine in 1727 for Edmonstone Colliery in Midlothian shows that the cylinder alone cost £250 out of £1,007 for the engine which did not include the cost of building the enginehouse nor the labour charges of the engine erectors.

The bucket pumps fitted to atmospheric engines were more suitable for raising a little water a great height rather than a large quantity of water a small distance. Then, the smaller engines did not work as well and were more expensive to run in proportion to larger ones which in any case consumed so much fuel that they were economic only either where fuel was cheap or where the product was very valuable. In the Cornish mines, the value of the ore had to pay for the expense of bringing from South Wales coal which happened to have a high calorific content. At this period, coal was transported in large lumps so that smaller pieces were regarded as waste and it was this waste which supplied the boilers of the engines pumping dry the coal mines.