his surprise, he discovered it was a pseudomucinous cyst that filled the whole abdomen and was histologically benign. Donald and MacVicar were pleased with the results from the machine and continued to experiment with how it could be used for diagnosis, but recognised that single dimension A-mode scanning was limited. The images produced by the device were still of poor quality and many still felt there was no future in the new machine. Donald learned of Douglass Howry's work in the United States, which found that an echo could only return to the probe and be recorded if the echo struck the reflecting surface at right angles as the laws of optics required. Brown felt that the A-scope presentation was incompatible with the nature of the problem, and that the image displayed did not correspond closely enough to the condition to enable a correct diagnosis. He believed that too much information was being returned in the image. For him, the problem was that there were many different echoes that were returned based on the number of body structures. Even the patient breathing or moving on the table affected the image. Brown saw this as a problem, and he planned to build a scanner that created an image that would be more useful for gynaecological diagnosis. Donald and Brown agreed to build a machine that used a rotating compound scanning search technique, like radar scanning a sector to increase the amount of echo information available. Contact B-mode scanner The solution proposed by Brown was to plot the position of the probe's echoes and create a two-dimensional picture. This type of device was known as a B-mode device. Unlike the A-mode device which used a single or double transducer and the function of depth to obtain a reading, the B-mode device uses a linear array of transducers that simultaneously scans a plane through the body that can be viewed as a two-dimensional image on a screen. To start building the new scanner, Donald sent a letter to Ted Smith, a London-based salesman of Kelvin & Hughes, which became part of Smiths Industries. At the same time, Brown also approached deputy chairman Bill Slater, who sent him to see Bill Halliday, the company's chief research scientist for an opinion on building the machine. After Brown delivered his spiel to Halliday, it was several months before Brown received a reply in the form of