It is used to precisely place an instrument tip in the x, y plane at any point along the length of the flow channel. The Instrument Carrier is an ancillary for use with Flumes range. The carrier consists of a base that fits to the rails that run along the top of the flow channel, and an upright that holds the instrument in position against scales that pinpoint its position. The carriage can be fixed at any point along the channel. Distances of the instrument in the carrier, with respect to other items in the channel, can be measured from this point. The position of the centre point of the carrier is marked by a slot in its edge.